i disagree. i think that the way it works now is best. in real life, it is close to Onikazi's CD analogy. more importantly though, if there were more benefits to choosing good choices, there would be no incentive to go evil. it comes down to taking advantage now, and paying later (evil), or paying up front, getting the advantage later (good). If more good benefits were implemented, it would be crippling yourself to go evil, which i don't think is the point.
if there were more benefits to going good, then there would need to be more benefits to being evil to balance, but i kinda like it becoming a choice of being future focused or present focused. it makes neutrality a form of Zen. it also means the same game can be vastly different due only to ethical choices. don't beleive me? start a game, save on the first turn, then play through as good, and see how it goes, then reload the save and play evil. alone, those choices change the game drastically.