I have often used snapshots of simple English Wikipedia, for young students learning English as a second language.  The simple snapshot was the most popular reading supplement for the youngest OLPC users.  It was the best resource on the web with a relatively uniform low-complexity level.  (Some of the ELI5 efforts are charming, but more entertaining than practical)

There is no easy way to extract such a subset from a mixed 'simple, normal, and advanced' English Wikipedia.  And unfortunately, most mixed-complexity-level wikis do not allow anything at the extremes: to simple or to complex and someone else rewrites it.

So: explicit tags with language complexity are needed. Until we have the tools and social norms to support a variety of different language standards (dialects, language level) on a single wiki, I hope we can sort the clumsy trading that is available —at the level of the entire wiki.

There is surely an audience for simple English wv and wb. And for similar things in other major languages (communities around which exist elsewhere online, if not yet in wikimedia).

I hope that lc-simple is now indeed valid.

SJ