But I do strongly think something should be done to stigmatize or coax users against heavy use of down voting.

Users should not be able to suck karma from the system as effectively as adding karma to the system. I'm pretty convinced there's a handful of folks very dedicated to cancelling karma they don't like, and who spend lots of time & effort undoing the hope & joy others seek to spread.

That's gross. I'd like to see something to push towards the positive.