RE: Compulsory Registration ?
Registration is about accountability. It's not about losing your anonymity. In fact, even in a forum without registration, the combination of the forum owner and your ISP can be used to track you down - registration does not even shorten this path.
Editing by forum administrators is possible with or without registration, and while seemingly giving some short term benefits to the culprit, is in fact very damaging to him or her.
Some other nice things about registration:
* Unless a user really wants to conceal his or her identity, it is very easy for all of us to know who we are talking to.
* Registration and sign in give you a better surfing experience, with private messaging and other nice features.
* Forums with named users (either registered, or voluntarily signed) are better at creating a sense of community.
* Trolls are easier to identify. Even if a troll want to invest a lot of effort, he or she can only create and post via so many accounts. Trolls are very easily busted when you don't have to guess their identities.