On the whole I think this is a great development for people who are looking to get wiki functionality in a corporate enterprise environment. As it has been stated before, Mediawiki was never designed with that intent in mind and so the people trying to make it work in that capacity rely on hacks and custom code to make it work for them.
Wiki markup is a barrier to entry for some people. It just is, for any number of reasons previously mentioned and more. I know I picked it up very quickly, spent some time with the docs and whatnot, but I'm fairly techy. As my Mediawiki deployment is on a corporate intranet I'm very nervous about the adoption of the system by the average user. I work at a very technical company and even then I don't expect more than 10% of our user base to actively contribute. Not knowing what the numbers are for Wikipedia, however, this may be about the right ratio regardless.
Not to be inflammatory, but I do see some of the points being raised here about elitism and "technocracy", and although I think it's more rampant in the Linux community (the most rabid of which seem to think any knid of user-friendliness is the mark of Satan), it may very well be a problem for wiki communities as well.
Fortunately there are solutions. If one truly feels left out or underprivleged it really isn't that hand to read some docs and work it out. Administrators can ease the burden by making quick reference pages easily available and providing the proper support and training to the user base.
Expecting to just "build it and they will come" is naive, especially in the corporate enterprise.