When we started Stack Overflow, we wanted to make sure that downvotes were more of a visual and psychological motivator than a punitive action. That's why
- upvotes are +10
- downvotes are -2, and cost the casting voter -1
However, recently, I've seen Marc Gravell and Jon Skeet both say similar things:
IMO, downvotes don't quite carry enough... -5 downvotes and +1 upvote (for sympathy) yields zero points overall; or it could even yield +10 points for a new user! I'd prefer to see, say, -4 points? -5 points?
I am starting to come around to this way of thinking. There are some users who ask a lot of questions that get downvoted heavily, but over time these users end up with a fairly sizable amount of reputation.
This doesn't feel right.
We are considering changing downvotes to -5, with the same -1 cost to the casting voter.
There really aren't that many downvotes in the system, so the net effect of this change would be to reduce rep growth for users who tend to get downvoted as much as they get upvoted. (Yes, I realize this is no panacea: over time, we'll still get rep inflation for marginal users based on sheer quantity; this is only one of several changes we are considering to help mitigate this.)
The other downside to this change, besides the obvious minor loss of rep for most users, is that it would force a global reputation recalc for every user. I think we're due for one of those anyway.