There's a rich history from older wiki communities and projects that we can, and should, draw upon, just as we draw upon existing sources for encyclopedia articles.
Maybe. I'm not actually sure that that's true; Wikipedia is a completely new thing. It's a wiki, but it's a lot more than a wiki.
Perhaps, but we're still building on a foundation that's largely wiki, and many of our problems have also been faced by other wikis. There are lots of other sources to learn from too: older encyclopedia projects (why did they fail?), commercial encyclopedias (is there anything we can leverage from them in our project?) and the rise(s) and fall(s) of other great Internet experiments (Usenet, Slashdot).
I think it's important to realize that we are on the bleeding edge here, and that the experience of others in other online communities, even wiki, doesn't necessarily apply. First, the idea that there is a "rich history" of wikis in particular is laughable, unless there's some definition of "rich history" that includes things created in 1995, none of which has ever produced a product even vaguely resembling what we're trying to produce. I might apply the term "rich history" to things like mailing lists, Usenet, IRC, and MUDs; everything else is new ground.
We also differ greatly from a lot of those earlier communities in that we have a goal: building an encyclopedia. We are not here /for the purpose/ of building a community; the community is just a /means/ to the end of building an encyclopedia. If those other communities teach us something about building communities, that may or may not apply here, because if the community gets in the way of the goal, the goal comes first. I think Wikipedia has more in common with things like open source software projects, in that the community itself is just a secondary concern to producing a product. In other words, we should take our lessons not from MUDs or Everything2, but from Linux kernel development, the Apache project, Mozilla, etc. I think it's worth noting that in all of those projects, there are security and control mechanisms.
So don't tell me what other Wikis have done--it doesn't matter. Tell me what other /successful productive projects/ have done. Don't tell me how to build a community; tell me how to make the community build an encyclopedia.