That way comments from users with good reputation having comments with more points by default. I know this makes the rich richer, but that's the way PageRank works too. If your karma/reputation doesn't make you to be heard more, what's the point of karma anyway?
This isn't really a reputation system, or if it is, the reputation is comment-based and not user-based. I don't see the karma of a user when they comment. I would need to click on the link of their name, what I never do.