Even if God is the creator, it doesn't necessarily follow we must obey "him" (outside of mere self-preservation).

That leads to the issue: why do what God says is right. If you do what God says, regardless, just because "He" is God, then there's no morality, only obedience. If you do what God says is right because you believe "He" is just, and his commandments and laws are right, you're using you're own moral judgement, which from a moral point of view makes God irrelevant.