My personal hypothesis is that much wikipedia incivility is part of
the broader internet-troll phenomenon (google "Don't Read The
Comments" if you're unfamiliar with the effects of trolling). I'd be
very interested to see a linguistic comparison between classes of
edits/comments tagged as 'bad' across a range of sites which allow
unmoderated comments.
Being able to confirm that large part of the problem was actually part
of an internet-wide problem rather than a local problem would be a big
step forward.
It worries me that the WMF may, by making the wikipedia interface more
similar to other discussion systems, reduce the differences between us
and the troll-infested platforms and make it psychologically easier
for those who troll on other platforms to troll on wikipedia.
cheers
stuart