(Disclosure: I'm Canadian.)
I find it hard to be evil in games, not so much because I don't like being evil (though I have a natural tendency for good), but because games with "moral choice" often make it difficult to be evil.
Part of this comes from the fact that 90% of the world is inherently good, while the other 10% doesn't care if you are good or evil, it's still going to bite your legs off. Additionally, good people don't like evil people, and their reaction will vary from running away screaming to trying to kill you in an ironic display of holy vengence.
The result is that being evil usually locks you out of very necessary things (like buying stuff at the local market), while it doesn't give you any benefit elsewhere (you still have to kill the imps that jump out at you ever 10 feet).
So really, being evil just makes the game harder. And if there's one thing I've learned about Americans (well, people in general, but Americans especially), it's that they like things easy.