This proposal only applies to protected/semi-protected pages, most of which are Biographies of Living Persons (BLP) for which Wikipedia already has stricter standards. There's a spin to this proposal that actually makes the encyclopedia even more inclusive, by allowing anonymous users who would ordinarily be prohibited from editing protected BLP articles to at least have their contributions reviewed.
If the deployment ever grows to cover more of the site, this sounds like something that would be rife with abuse, and even though it doesn't sound like that's the plan, it's interesting to think about how you might want to solve that. One of the things it suggests is the need for wikipedia to involve democratic trust metrics (i.e., you aren't an admin just because you're friends with another admin) but this invites its own host of problems. Interesting topic though.
As wikipedia matures, they won't be as desperate for article contributions. So they won't need to take the risk of having bad data. This is a natural progression.
I think Wikipedia is facing a myth vs. reality problem: the idea of an freely editable encyclopaedia is wonderful, but in the end a closed & moderated system might prove more useful.
I think it's misleading to call Wikipedia an "idea" at this point; it very much is a freely-editable encyclopedia; it is already a superior substitute in the market for encyclopedias.