I agree that the Wikipedia: namespace is way too full, but I'm not clear what sort of information we should put in Wikipedia: , we also have a Help: namespace, and that looks like a good place for "manual" type info, and currently has copies of pages from meta, and Wikipedia: seems like a place for policy decision.
So am I missing something? What's the purpose of Wikipedia: and Help:?
If we have answers to this already, I think we need to make them more clear, as Wikipedia: seems a mixture of both.