I, personally, don't downvote as a way to express disagreement. The average redditor does. I wish it was reasonable to expect that the entire reddit community uses downvotes only in a way I consider appropriate, but I don't think it is.
I think every voter should get their own list of sorted stories and comments. That list should form based on voter's upvotes and downvotes.
Then readers would quickly stop seeing postings they are likely to downvote and see more postings that they are likely to upvote.
Pretty soon people who express their interest in controversy - would get controversial stories on top of their list and people who express their interest in groupthink - would get lots of stories re-confirming their groupthink.
