I haven't clicked on any of the above links yet, but God DID warn Adam and Eve.
He told them they could eat of all the trees but this one.
I think it boils down to disobedience.
Whether the tree was actually evil......
it was the tree that stood for the choice Adam and Eve had to make.
Eve chose to eat from the tree, being disobedient and her husband followed.
God gave a temptation and a demand.
Man was weak and gave into this temptation, disobeying God.