I've been pondering this for a while, but the regular vandalism and joke edits, even the ones where the problem user undoes it themselves straight away, can easily be stopped by requiring every editor to log in. I know from experience of being around wikis that have done just this that it works as vandals cannot hide behind anonymous ip addresses and have to make more of an effort in order for their edit to go through.
I thought about doing this a good while ago, even though it goes against the ideal of a wiki that everyone should be able to edit even without an account. I decided to watch and see if there were any positive edits by anons. However, other than undoing vandalism (thank you to those people btw), bad edits seem to be the only contribution coming from anon editors, with the real work coming from people with accounts. And those real efforts are being attacked constantly which is becoming very annoying.
So what do people think of this? Should we force everyone to edit logged in or allow the current situation to continue?