Enforcing real names is a good thing. It means people finally start to take responsibility for their actions, and there is accountability. People behave much better when the threat of embarrassment is in the balance.
I only see one legitimate reason for someone to be allowed a pseudonym: if they are more widely known by that name than their real name. This applies to authors, artists as well as web community members. The solution is easy: allow a nickname field in addition to your real name: [First] "[Nickname]" [Last]. Some already do it. Day9, for example, goes by Sean "day9" Plott online.
Lastly, I realize the hypocrisy of posting to Hacker News without my name visibly attached, so for the record, I am Kenneth Ballenegger from kswizz.com.
[1]: I have browsed thru /b/ many times, and the behavior of people there truly is the worst I've seen ever. I was in the middle of the SF Giants riots last year, and the people setting fire to cars and breaking windows seemed more civil by comparaison.