In general I would agree, and I would agree that people should do their part in up (and down) voting comments. But to me, with no scores visible, I hardly notice the impact. I always read all the way down the page, and rather than trying to work out how high a comment has been voted based on its position on a page, I just ignore it.

So I'd rather chose to not have any votes and actually get something out of other people's votes than to have an impact that nobody can actually see.