Why do people want ten Wikipedias to look up instead of one?
Why would people want millions of computers instead of just eight? Why would we want terabytes of memory when we could have just 640 kilobytes? When I go to the library, why are there a gazillion books, instead of just "the best book"?
Why do people want simple english wikipedia, when they could just have english? Why do some people want a "Scientific Point of View" at Rationalwiki or a Conservative Point of View at Conservapedia or a sympathetic point of view? Just because Neutral Point of View is, in my eyes "the best", that doesn't mean we don't want to read other points of view.
A better question is-- why do we want there to be ten Wikipedias instead of just one? And the answer is-- to recruit their users and to copy their best ideas. :) The more people familiar with wikitext, wikis, the wiki concept, and the wikimovement, the better.
A distributed wiki proposal needs to clearly solve a problem the readers have.
There are a lot of real problems that readers have that this could be helped with. Technologically the most obvious is the "Offline Reader" problem. If offline readers would, for example, would prefer to be offline editors-- they'll need this.
The problem I'm most excited about is the "The Wikipedia-Article Quality Problem"-- we all know that Wikipedia's a pot-luck. Sometimes an article is wonderful, sometimes it's horrible. Most importantly, many of our articles aren't necessarily getting better with time, and in some instances they seem to be eroding away as editors realize that there's "no point" to putting too much polish on an article that's under such active development. In this light, distributed development would be a little like Flagged Revision, only far far more powerful.
Another problem readers have is the "Openness Problem"-- namely, our readers would love to be editors if they had a way that worked for them. For whatever reason, these people can't handle the full-blown Wikipedia experience. We're not sure whether it's the massively-peer-reviewed culture or the highly-templated wikitext code that's the larger barrier, but the fact is, some readers just can't handle Wikipedia, so instead they're choosing not to participate at all, even though the have the inclination to.
Lessons from distributed revision control suggest that a small "sandbox space" feeder project would be more inviting. It would let experts who know how to write in a pre-wiki style come as they are, and help contribute without having to change themselves or their writing style. On Wikipedia itself, the usual process would then take over and use good parts from these articles to make an even better Wikipedia article.
Supppose "I" am a prestigious, recently-retired science professor willing to spend time working on one of our projects. Imagine all the BS I will have to put with. Just think about all the hoops I will have to jump through-- learn wikitext, learn wikiculture, learn the rules, hand being insulted, handle having people who know less than I do incorrectly delete my correct contributions. "I"'ve spent a lifetime in one kind of culture writing one sort of way, and I've been getting a lot of respect for it. If I want to help here, "I" have to learn computer code, learn a new culture, learn a very new and different writing style with lots of different rules, and I have to deal with being disrespected by people who know less about the subject than I do. (again, I am none of these things myself, but I'm such such people exist)
The "Lesson of Git" is that we really should be letting these people just "come as they are" and start writing for us, with the knowledge that some of it will be good, some of it will be bad, but as long as it's all written in good faith, the net effect on our project will be positive.
This solves a problem for the *writers*, but makes one for the *readers*.
This should not be confused with Wikipedia article forks, that's a whole different question that bares only the tiniest of similarities. The reader experience, for true readers and only readers, wouldn't be different at all. They go to wikipedia, there's an article in the same place it's always been, and the article is our editor's version, just like it is now.
The editor experience for most editors wouldn't necessarily be different unless they wanted it to be. -- Lastly, I don't see this new model just "taking over" Wikipedia-- Wikipedias might always use the current model. and that'd be fine. Either way, we could use satellite 'specialist' projects' that used the new model. It'd be up to the Wikipedia community to figure out how best to use that information-- but it would help us to have it.
Alec