This has topic-drifted like mad, so please excuse this as being a collection of utterly unrelated material.
One of the things that has bothered me is the way in which Wikipedia has tended to attempt to take over from more specialized efforts which are surely more authoritative than anything we can produce. I've seen this in a lot of science and transportation subjects, as (for instance) the tendency to write articles on every train station that ever existed, and then put in all information short of actual arrival and departure times. This stuff is high maintenance and particularly where there is an official site, any sensible person should prefer that over us. It would be nice to come up with some way to turn ourselves into a portal to the good (meaning reliable) stuff for these subjects.
As far as AGF is concerned: someone way up the chain hit the main reason. In decades of on-line discussion, I've found no principle more destructive than the "sovereign right to take offense". Even true trolling is not as bad (and it seems to me that most of what is called "trolling" these days is actually the SRtTO). In order to for you to make rational discussion, it is necessary for you to view your opponent as someone you could discuss things with rationally.
The flip side is that the visibility of Wikipedia means that there are way too many people who have something (malign) to gain from gaming it. The obvious result is that bad faith is increasingly abundant; the less obvious result is that the resulting urge to conduct a crusade against bad faith leads people to self-righteous responses. There are a lot of subjects which one probably shouldn't edit over long periods, because the POV warring is so strong that it is eventually possible not to be contaminated by it.
Which leads me to something that will undoubtedly rub some people the wrong way. Wikiprojects attract people who love the subject in question. This is always a recipe for some bias, as (for example) people in the Trains Wikiproject are likely to have positive leanings towards trains, and perhaps especially the trains of their native land/region/railroad. I don't know how much we can do about that, as banning projects or other overt associations isn't going to stop people from associating. The ones that worry me are those that are formed around advocacy points, and especially those addressing current controversies. For instance, one can go to the Intelligent Design project page and see complaints that it (and therefore the articles under its sway) are owned by committed secular Darwinists. We also have project on LGBT studies and on animal rights which surely must function as rallying points for those who support the same. Argument about how accurate these perceptions are is a bit beside the point; if the projects themselves are free of bias, there are surely subcommunities of editors who aren't.
I don't have a nice summary to tie all this together, so I'll just top here.