It's well-known that writers of speculative fiction, especially those exhibiting secondary worlds for their stories, take an iceberg approach to such things. They write down so many notes about things regarding the world that the lore so generated often becomes an selling point to itself; the enduring allure of Tolkien's Middle-Earth is the most famous example, but there are other examples in all the major genres- and not just written forms (e.g. Star Wars).
We no longer need to either file those papers away to be revealed never, or only long after the books that came from them have become some form of classic. We have the means, here and now, to make those papers part of an ongoing marketing effort that helps to sell not only new books in the series but also that increasingly-larger backlist of previous books. Wikis are that means.
The successful launch of Infogalactic shows that you can use the wiki technology without letting every last motherfucker on the planet having access to it. You can lock it down, and only put out what you want; the rest just get to read it. This is a way to allow you to make use of what you do with your world-building as a means of promoting yourself, your brand, your works, and those of your collaborators while you finish work on the manuscripts that you do this world-building for.
I'm going to give this a go in the near future, once I generate enough material to merit the work of putting one up. When I do, I'll put out a call for help because it'll be new to me and I could use a hand or two.