As someone who has put a lot of work into Wikipedia, I have reluctantly concluded that in order to move forward as a project we have to stop letting people edit as anons.
I believe in the spirit of the project but I am unconvinced that the current requirements for account creation form any real barrier to being the free encyclopedia that "anyone can edit". On the other hand, many good editors have the valuable time that they are able/willing to contribute eaten up by fighting anon vandals. Probably 1/5 of what I do on Wikipedia is revert or rollback vandalism by anons to the pages on my watchlist. While that looks great for an edit count, in terms of productivity it only represents wasted time. Someone indicated to me that the turn-over rate for seasoned administrators has become unusually high. I have no hard evidence but I don't think it is unreasonable to think that part of it is being bored with just blocking anon vandals and not having time for much else. If the project were able to free them up to do more productive, interesting things more of them would stay longer.