To understand the event we must understand the cast of characters especially Jethro, Moses' father in law.
Jethro, the priest of Midian
Midianites - An Arabian tribe descended from Midian. They inhabited principally the desert north of the peninsula of Arabia. The peninsula of Sinai was the pasture-ground for their flocks. They were virtually the rulers of Arabia, being the dominant tribe. Like all Arabians, they were a nomad people. They early engaged in commercial pursuits. It was to one of their caravans that Joseph was sold (Gen 37:28, Gen 37:36). The next notice of them is in connection with Moses' flight from Egypt (Exo 2:15-21). Here in Midian Moses became the servant and afterwards the son-in-law of Reuel or Jethro, the priest. After the Exodus, the Midianites were friendly to the Israelites so long as they traversed only their outlying pasture-ground on the west of the Arabah; but when, having passed the southern end of Edom, they entered into the land of Midian proper, they joined with Balak, the king of Moab, in a conspiracy against them (Num 22:4-7). Balaam, who had been sent for to curse Israel, having utterly failed to do so, was dismissed by the king of Moab; nevertheless he still tarried among the Midianites, and induced them to enter into correspondence with the Israelites, so as to bring them into association with them in the licentious orgies connected with the worship of Baal-Peor. This crafty counsel prevailed. The Israelites took part in the heathen festival, and so brought upon themselves a curse indeed. Their apostasy brought upon them a severe punishment. A plague broke out amongst them, and more than twenty-four thousand of the people perished (Num 25:9). But the Midianites were not to be left unpunished. A terrible vengeance was denounced against them. A thousand warriors from each tribe, under the leadership of Phinehas, went forth against them. The Midianites were utterly routed. Their cities were consumed by fire, five of their kings were put to death, and the whole nation was destroyed (Jos 13:21-22). Balaam also perished by the sword, receiving the "wages of his unrighteousness" (Num 31:8; 2Pe 2:15). The whole of the country on the east of Jordan, now conquered by the Israelites (see SIHON; OG), was divided between the two tribes of Reuben and Gad and the half tribe of Manasseh.
Some two hundred and fifty years after this the Midianites had regained their ancient power, and in confederation with the Amalekites and the "children of the east" they made war against their old enemies the Israelites, whom for seven years they oppressed and held in subjection. They were at length assailed by Gideon in that ever-memorable battle in the great plain of Esdraelon, and utterly destroyed (Jdg. 6:1-ch. 7). Frequent allusions are afterwards made to this great victory (Psa 83:10, Psa 83:12; Isa 9:4; Isa 10:6). They now wholly pass away from the page of history both sacred and profane. - (Easton's Bible Dictionary)
Jer 19:5 They have built also the high places of Baal, to burn their sons with fire for burnt offerings unto Baal, which I commanded not, nor spake it, neither came it into my mind:
Exo 18:1-27 When Jethro, the priest of Midian, Moses' father in law, heard of all that God had done for Moses, and for Israel his people, and that the LORD had brought Israel out of Egypt; (2) Then Jethro, Moses' father in law, took Zipporah, Moses' wife, after he had sent her back, (3) And her two sons; of which the name of the one was Gershom; for he said, I have been an alien in a strange land: (4) And the name of the other was Eliezer; for the God of my father, said he, was mine help, and delivered me from the sword of Pharaoh: (5) And Jethro, Moses' father in law, came with his sons and his wife unto Moses into the wilderness, where he encamped at the mount of God: (6) And he said unto Moses, I thy father in law Jethro am come unto thee, and thy wife, and her two sons with her. (7) And Moses went out to meet his father in law, and did obeisance, and kissed him; and they asked each other of their welfare; and they came into the tent. (8) And Moses told his father in law all that the LORD had done unto Pharaoh and to the Egyptians for Israel's sake, and all the travail that had come upon them by the way, and how the LORD delivered them. (9) And Jethro rejoiced for all the goodness which the LORD had done to Israel, whom he had delivered out of the hand of the Egyptians. (10) And Jethro said, Blessed be the LORD, who hath delivered you out of the hand of the Egyptians, and out of the hand of Pharaoh, who hath delivered the people from under the hand of the Egyptians. (11) Now I know that the LORD is greater than all gods: for in the thing wherein they dealt proudly he was above them. (12) And Jethro, Moses' father in law, took a burnt offering and sacrifices for God: and Aaron came, and all the elders of Israel, to eat bread with Moses' father in law before God. (13) And it came to pass on the morrow, that Moses sat to judge the people: and the people stood by Moses from the morning unto the evening. (14) And when Moses' father in law saw all that he did to the people, he said, What is this thing that thou doest to the people? why sittest thou thyself alone, and all the people stand by thee from morning unto even? (15) And Moses said unto his father in law, Because the people come unto me to enquire of God: (16) When they have a matter, they come unto me; and I judge between one and another, and I do make them know the statutes of God, and his laws. (17) And Moses' father in law said unto him, The thing that thou doest is not good. (18) Thou wilt surely wear away, both thou, and this people that is with thee: for this thing is too heavy for thee; thou art not able to perform it thyself alone. (19) Hearken now unto my voice, I will give thee counsel, and God shall be with thee: Be thou for the people to God-ward, that thou mayest bring the causes unto God: (20) And thou shalt teach them ordinances and laws, and shalt shew them the way wherein they must walk, and the work that they must do. (21) Moreover thou shalt provide out of all the people able men, such as fear God, men of truth, hating covetousness; and place such over them, to be rulers of thousands, and rulers of hundreds, rulers of fifties, and rulers of tens: (22) And let them judge the people at all seasons: and it shall be, that every great matter they shall bring unto thee, but every small matter they shall judge: so shall it be easier for thyself, and they shall bear the burden with thee. (23) If thou shalt do this thing, and God command thee so, then thou shalt be able to endure, and all this people shall also go to their place in peace. (24) So Moses hearkened to the voice of his father in law, and did all that he had said. (25) And Moses chose able men out of all Israel, and made them heads over the people, rulers of thousands, rulers of hundreds, rulers of fifties, and rulers of tens. (26) And they judged the people at all seasons: the hard causes they brought unto Moses, but every small matter they judged themselves. (27) And Moses let his father in law depart; and he went his way into his own land.
So here we have the true story of why Moses went up into Mt. Sinai to ask God for laws. It was not at God's beckoning or part of his plan to give Moses the "LAW". It was all Jethro's idea. Moses, after hearing Jethro tell him what he was doing was wrong, never consulted God. He just did as Jethro told him to do. With words reminiscent of those spoken in the Garden to Eve (Gen 3:1 Now the serpent was more subtil than any beast of the field which the LORD God had made. And he said unto the woman, Yea, hath God said, Ye shall not eat of every tree of the garden?) and those spoken to Jesus in the "wilderness" (Mat 4:3 And when the tempter came to him, he said, If thou be the Son of God, command that these stones be made bread. Mat 4:6 And saith unto him, If thou be the Son of God, cast thyself down: for it is written, He shall give his angels charge concerning thee: and in their hands they shall bear thee up, lest at any time thou dash thy foot against a stone.)
Don't forget Jethro is the high priest of Baal. He never repents and rejects his god. There is no statement that he accepts Jehovah as his god. Even Satan refers to God as God he just never submits to God as his God. Jethro is also a "Kenite", a descendant of Cain .
Judges 1:16 And the children
of the Kenite, Moses' father in law, ...
Once Moses had appointed hundreds of judges as Jethro had instructed they were helpless. All these judges and not a single page of laws to enforce. The only thing left out of the Biblical account is the part where all these judges say "Well, what do we do now? Moses we need LAWS!"
Everything Moses does at Mt. Sinai after his conversation with Jethro becomes somewhat the "fruit of the poisonous tree" and that is why the Apostle Paul writes about the event as something that must be treated as never having happened.
Heb 7:18 __there is verily a disannulling of the commandment going before for the weakness and unprofitableness thereof.
Also Paul's comparison between Moses going into Mt. Sinai to receive the Law and Abraham having sex with his maid as an allegory (What is an allegory? Webster's dictionary defines an allegory as a literary, dramatic, or pictorial device in which characters and events stand for abstract ideas, principles, or forces, so that the literal sense has or suggests a parallel, deeper symbolic sense.)
Gal 4:24 Which things are an allegory: for these are the two covenants; the one from the mount Sinai, which gendereth to bondage, which is Agar. (25) For this Agar is mount Sinai in Arabia, and answereth to Jerusalem which now is, and is in bondage with her children.
The Hebrews are delivered out of bondage in Egypt by God then turn around and are brought back into bondage by the "LAW". Paul begs the question of returning to bondage again after Christ has set believers free from the "LAW":
Rom 8:15 For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.
Gal 2:4 And that because of false brethren unawares brought in, who came in privily to spy out our liberty which we have in Christ Jesus, that they might bring us into bondage:
Gal 5:1-4 Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage. 2 Behold, I Paul say unto you, that if ye be circumcised, Christ shall profit you nothing. 3 For I testify again to every man that is circumcised, that he is a debtor to do the whole law. 4 Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace.
If "God's will" was to bring everyone into bondage to the "LAW", why did Christ have to come to set us free from the "LAW". If Christ came to do "only" the "will of God", why is he the author of a better covenant? What! Did God make a mistake on Sinai or was the "law" another concession? By concession I mean God will sometimes give us what we want not what we need because he loves us so much. Here God gives the Hebrews the "Law". Not because it was what He wanted, but because the people wanted it. When Israel wanted a King God conceded and gave them a terrible king, Saul. When they wanted laws He conceded and gave them laws that He knew they could not fulfill. Other evidence that the "Law" was not God's will is demonstrated by the events surrounding the giving of the law. While Moses was on the mountain receiving the law events unfolded at the foot of the mountain that God had to know were happening. An individual commissioned a golden calf to be made and then gave the order for the people to get naked and begin only what could be called a drunken orgy.
Exo 32:18 And he said, It is not the voice of them that shout for mastery, neither is it the voice of them that cry for being overcome: but the noise of them that sing do I hear. ( In verse 18 "sing" is "abase themselves" Strong's Concordance)
Exo 32:24 And I said unto them, Whosoever hath any gold, let them break it off. So they gave it me: then I cast it into the fire, and there came out this calf.
Exo 32:25 And when Moses saw that the people were naked; (for Aaron had made them naked unto their shame among their enemies:)
Exo 32:35 And the LORD plagued the people, because they made the calf, which Aaron made.
It was while this was happening God told Moses that the High Priest of this "Covenant of Law" was to be this same person Aaron, the biggest sinner of them all. Surely if the "Law" was God's plan and not a concession he would have picked a person of moral character that loved Him, not Aaron. If God's plan for Israel was to have a King he would picked a man like David not Saul. The Scriptures say that God wanted to write His law on the hearts of his people and the "King of the Jews" was for His son to fulfill. The timing of God and His Will has been hindered and postponed throughout history by a stubborn and stiff-necked people who insist on having things their way. It cost the children of Israel forty years in the wilderness on one occasion and four hundred thirty years in bondage to the Law on another. On other occasions His people were enslaved by foreign nations, occupying armies or slaughtered. In every case it was their lack of attention to God, His timing and his will that brought it about. Most of his children are still in bondage to the "Law". It is the God's will that all of His children to step into and embrace the "Law of Liberty" wherein Christ has set us free.
Jam 1:25 But whoso looketh into the perfect law of liberty, and continueth therein, he being not a forgetful hearer, but a doer of the work, this man shall be blessed in his deed.
Jam 2:12 So speak ye, and so do, as they that shall be judged by the law of liberty.
Joh 8:36 If the Son therefore shall make you free, ye shall be free indeed.