Therein lies the the problem though. It seems to be the general consensus that people should down vote only for unhelpful / irrelevant / factually incorrect comments, however voting is used to show agreement / disagreement. Before voting, I usually ask myself why I'm doing this. If it's to promote an opinion, I leave it alone.
Exactly. Down-voting is not to show disagreement, it's to cull comments that don't contribute to the discussion. What I'm proposing would hopefully make people question their motives before down-voting.