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After I vote, I see up votes and down votes (except for the "no significant downvotes" business). I sometimes vote up well-thought nodes with which I wholly disagree and respond with my reasons. I sometimes down vote poorly and rudely written nodes despite agreeing with their main point.
Taken as a whole, I think contention of the ideas in the node is poorly measured by votes. A contentious attitude or heated words might lead to the votes without any useful ideas being debated. If you measure it, someone's going to want the highest score in it, too. Fishing for hot responses is what trolls do. Don't feed the trolls.
If you want a decent measure of active discussion, count the tree of descendants of a node. That should be simple enough and informs the reader just as much about the node. There are a few long branches of PM that arise from polls, reminiscent meditations, and such. Most root nodes, though, involve more discussion as there are more responses and more levels of responses to responses.
BTW, I voted ++ on your node because I think you're on to something and I appreciate that you're thinking of how to help the site. This is one of those, though, that I voted ++ for yet disagree with your initial conclusion.