I know what you mean, and I agree. The game certainly does lean towards being a good guy. But I think it's pointless for someone, Yahtzee or otherwise, to give the complaint that even though you have the choice to be evil, you have no reason to be. Having more choices in a game is a good thing, but to whine that the developer isn't giving you a reason to make a specific choice is dumb. The reason for making a choice is your own thoughts, beliefs, morality, what have you. If you want to be evil, you'll choose to be evil. If you really want to be evil, you'll choose to be evil even when the game is leaning towards you being good.
On a side note regarding your complaint about how being evil is too hard, it's about time they made a game where being the good guy is easier than being the bad guy.