At this time, brethren, when God was about to begin His formal governance of Israel, His people, those who had consented to be ruled by Him, there was nobody between them and God. There was no governmental structure. God spoke to them face to face, and they rejected it!
I believe that Exodus 20 was indicating that God was prepared to do for the entire nation of Israel the same as He had done with Abraham, with Moses, and with others as well. But He presented Himself in such a way as to impress upon them the weighty responsibility of such a situation. (Paul said, "Our God is a consuming fire.") And they quickly chose a mediator to stand between them and God.
