God invented everything - He could have it any way He wanted it. There are no restrictions on God. And when it came to the sin problem, He had the option to solve it any way He wanted to.
I have wondered for a long time why He choose to solve it the way He did. The easiest and least painful way would have been to just erase everyone's memory that sin ever happened; it would never have been an issue - no one but Him would have ever known it ever came up!
This is not exactly like forcing someone to make a certain choice - they'd just forget that someone else had made that choice once.
But would it be totally honest? He'd have to manipulate our minds - even ever so slightly, to keep it a secret.
So, way did He not do this? Is it that God doesn't want a bunch of mind-altered robots running around praising Him?
Well, I don't think He does. But I also think it goes way beyond that. To make us all forget that sin had been a part of life would be an act of deception. Yes, I know, no one would be aware of this deception - well, no one except for God Himself. And there in lies the truth!
God must remain true to His character. He cannot be the "truth" and be deception at the same time.