> It seems like if something is getting a lot of comments and generating discussion, whether a post or another comment, it should be rewarded.
This is a misconception -- upvoting isn't a reward, and downvoting isn't a punishment. People upvote comments to increase their visibility, and downvote them to decrease their visibility. Voting is about personal taste, not the making of moral judgments.
> I see way too many <= 0 comments that have a big discussion associated with them which often speaks to the value of the comment itself.
Another misconception -- the fact that a submission creates a lot of comment isn't necessarily a reflection of the value of the submission -- the original might be deplorable, but how and why it's deplorable might merit comment.