This may be an unpopular theory, but I think Wikipedia's shrinking community has little to do with the admins behavior. I've only personally heard about their poor behavior from 3rd, 4th, or 5th hand accounts. But that's purely anecdotal and a side-tangent.
I think the reason the community is shrinking is because Wikipedia, at least the English version, is complete. I'm not implying that there isn't more information that can be added, but as far as the sum of human knowledge goes, I'd guess that they have gotten past that "magic" 95% marker for easily acquired knowledge. Most of the remaining work to be done is article maintenance, and filling in mundane details of niche articles or emerging fields. The days when 5th graders wrote articles on your home town or park near you is gone. My quaint home town article for Rockford, MI
(a town with less than 5000 people) is nearly 3 pages long! (I can't believe there was enough to even fill in 1 page, after the generic census data...
This isn't a bad
thing. It's the natural evolution of such a site. Wales should pat himself on the back and congratulate the community for his contribution to society as a whole. Wikipedia is a job well done and has moved our world forward in a positive direction, in what is becoming a rarer achievement every day.