This policy change is NOT wikia wide.
It's not wikia wide because not all wikia deal with content that attracts children. Of course this policy doesn't affect wikis such as Assassin's Creed or Silent Hill or something, because those wikis deal with mature content, whether it be text or screenshots. That's not to say that there aren't underage users there, but they are a different category. This policy is going to primarily affect the more family oriented wiki that are out there, especially the large ones, such as ours.
Essiw wrote: ^We are talking about the Dragonvale wiki community, not about the DV game community. About your question "does anyone need to contribute?", if no-one did the wiki wouldn't be here, the anons are part of the wiki contributers...
Wording it like that is kind of a slippery slope. Would we be where we are without anonymous users? Maybe, maybe not. Many have been quite helpful and no one is denying that, but the bulk of the work has been done by registered users, not anonymous editors. And indeed, some anonymous editors did end up becoming some great registered editors, but the vast bulk of the anonymous contributions on this wiki are article comments. And if that's an issue, we'll just have to figure out someplace to direct anonymous users so they still have a social link, if it can no longer be on this wiki.