Wikipedia's license allows you to fork the articles and take them in any direction you like. They just wont host it for you.

Yep, the open data makes it possible. The unified UI is the key feature here, so that we can contrast and compare the various takes from one place. It doesn't work if they are spread and unlinked, across the web. Basically, take every article in the corpus and make it one leaf in a bush. The Wikipedia version can remain canonical for those who want it to.