The relationship that the Israelites had with God is at best a warpt realtionship that is only a vague reality of the oldness of the letter. It can not and will not in any way be compared to the relationship a being ha s with God but mediated by angels to bring the messiah into play and thereby giving way for the real thing.
It is a known thing that the parlance of relationship between the Israelites and God was a vague picture of what it wanted to accomplish in the death of Christ, because, the old was at best the shadow of the real thing.
Why would he decide to bring the old covenant if it was useless to them?
Why waste their time and not start the new from the very beginning?
What is the the question of asking why God related to people based on the former and not on the new right from the start?
First I would like to say that God is not operational and does not deal with time and does not define time, and would not be limited by time so it does not differ with him whether it was
a billion years ago or now but one thing I'm positive about is the fact that He is perfect.
I would say why would you should check out this post of this wonderful site that talks about the concept of what was on the mind of God before He created the world and why he chose the concept of creating the garden of Eden and why he chose the serpent
https://www.ucg.org/the-good-news/what-did-god-plan-before-time-began
