In Moses' day, the way you honored and respected whatever gods you followed was by making carvings or sculptures of them and then bowing down to what you had made. These were gods you could get your mind around. Moses is confronting people with an entirely new concept of what the true God is like. He is claiming that no statue or carving could ever capture this God, because this God has no shape or form.
Rob Bell, Velvet Elvis, p. 23
Perhaps Bell can tell us, please, when Abraham, Isaac, or Jacob made carvings and sculptures of God. Maybe he can tell us when the people who were in slavery in Egypt had taken up build such sculptures and statues.
Funny how we don't see that among them. Funny how we see the fathers building alters, but never statues. Maybe it's like they didn't see the need. God spoke to them, God called them, God made promises to them, God even consults them at times, but they don't make images of Him.
Maybe the people did kind of want a god they could see, kind of like in Egypt. Maybe that's one reason they made the golden calf. But that was the new idea, not the old one.
As such, then, Moses isn't confronting them with "an entirely new concept", but rather with an old one, one that goes back to the founders of their nation. If anything, such things as the golden calf represented new ways, things they likely picked up in Egypt, things they had to unlearn and set aside in order to return to the truth about the God of Abraham, Isaac, and Jacob.