A question: is Wikipedia the first online community you've been deeply involved in?
(Not that this is a bad thing on your part, I'm just asking. I suspect that this being the case for a lot of people is a lot of the perception of the problem. I just find myself repeatedly surprised at people talking about Wikipedia's problems as if they're novel in any way.)
I've been involved in plenty of online communities, but none quite like Wikipedia. Even if the basic problems are the same, the standard solutions often don't apply. For example, in most online communities its not a problem to have admins (or the equivalent) taking charge of things as opposed to just doing janitorial work as they do on Wikipedia. Wikipedia admins giving orders would be very unpopular. Also, there is the simple matter that Wikipedia is much bigger than most online communities. Whenever I've been involved in an online community that was too big for true consensus driven decision making to work there has always been people (usually paid staff) in absolute charge. Wikipedia doesn't have that (the foundation don't intervene in the day-to-day running).