A problem with citing Wikipedia, other than the obvious "it's human-edited so it contains human errors" (which is true for pretty much every other source as well), is that you can edit the Wikipedia page you're citing *before* you're citing it to effectively construct any argument you want. If I want a Wikipedia citation saying "Seth has an IQ of only 89" then I can have it right now, by editing your page to my liking and then copying from the page before my edit gets reverted by a Wikipedian.