Better integrate Mediawiki with external editors (free source also) is best solution, not only in my case, but also generallly?
it's not difficult if you know how. I use BBEdit and Applescript to edit pages. I have complete non-geeks editing pages happily. How can wiki text get 'heavily marked up'? anyway? It's not that bad, however bad it is (we're not talking HTML, are we?)
WYSIWYG is usually very poor under the hood - I don't even use Word Processors any more. Trying to do some kind of Dreamweaver would be really over the top! As for Word import, it hasn't worked with any other Word Processor properly (believe me, I've tried...) so what's the point?