As of 12:30 EST on November 15th, there were 30,658 registered users of Stack Overflow, of whom 1,458 had at least a 750 reputation and could therefore edit Community Wiki posts.
I suggest that if only 4.75% of the community can edit a wiki, it is neither "Community" nor "Wiki". The average technical question or answer seems to get one or two upvotes, and so a user who wants to become "trusted by the system" would have to post around 40 questions and/or answers before becoming "trusted". This can take longer if the user's expertise is in a niche, since people can't vote for questions and answers they don't read in the first place. The bar should be lowered to 250 points.
This would be a silly argument on slashdot, where karma only means your posts get a bonus point. But on SO you need reputation to take full advantage of the site. The intention of SO is to serve as a reliable repository of programming and programming-related knowledge, but the reputation system incents people to post frequently and quickly so they can "earn the system's trust". It also encourages people to add to the cacophony rather than to the community, because you only get points by having non-CW questions and answers. A quiet comment may add just as much value, but a whole new answer might result in 10 points and being able to take advantage of more of SO's features.
Meanwhile, a person with niche expertise who monitors, maintains, or adds valuable information to older questions contributes just as much to the site, but gets rewarded less for it. That's not very wiki.
Another point I'd like to make is that there is an aversion to discussing SO on SO, especially if it's for reputation points. Why? First of all, the user interface of this website is the balls. There are a few things that could be added or tweaked, but overall it's one of the best interfaces I've ever used. Second, this is where the SO community will see it. Uservoice is not nearly as popular and it has a lot of limitations (like needing to have votes to ask questions) that SO doesn't have. Third--and this is the important one--I think that participating in the community SHOULD earn reputation points. For all its warts, the people who have the most juice on Wikipedia are the ones who care most about Wikipedia; not the expert on banana slugs who keeps the Banana Slug article up-to-date.
I really like this site. I've been pleased to get quick answers to some programming questions. I've read some really solid advice about design and project management. And the other users are generally smart and nearly always friendly and helpful. I'm not whining about the site or complaining about it; I'm just trying to help it become what it was intended to be because I think it would be a net gain for us all.
And I'm not making this community wiki, either. I invested a lot of time in writing it, I believe in what I said, and if the SO community agrees with me then there's no better way for the system to indicate that it "trusts" me then to increase me authority on the site. (And if they disagree I'll lose points and authority; so the reward is balanced by the risks.)
[Note it's tagged appropriately so if you don't like these types of "questions", just filter out the tags.]
EDIT: This "question" has received 13 net votes in the last 12 hours. My other questions (well, 4 out of 5 of them) are specific questions about programming issues and they haven't received more than 5 votes in the last month. This illustrates why there are so many soft questions (or "questions with broad appeal"), as well as points out that there are a lot more people on SO with an opinion about SO than there are people with an opinion about--say--XSLT.