But if naivete was any part of the failing for which Eve was punished in Gen 3:16, did God himself not fail in making her less naive?

This goes straight to the root of the matter, because the tree they ate from was that of the Knowledge of Good and Evil. On the above exegesis, that knowledge was precisely familiarity with the blessings and curses of a life lived outside of the care of God. God could not have given Adam and Eve such sophistication without putting them into an adult frame of mind, giving them just that sort of knowledge conveyed by the tree of that name. God did not want to give them that knowledge, but made it possible, through the presence of the tree and by permitting a serpent to tempt them to take it. By taking it, they got precisely the sort of knowledge that might have made it possible to avoid that particular temptation.