Yes I like that you can choose whatever name you want, but ask your family members or old friends from school how they use Facebook. Being enable to find old friends and connect with far relatives is a huge reason for why Facebook is so popular. I am having a hard time time figuring out how to solve this problem if there aren't any constraints, culture or expectations for using real names. Maybe it's just a matter if time. Online aliases is more second nature to the coming generations. And still, the group and chat thing is very important imho. That's why I asked about XMPP. Would love if we could get a modern chat system as widely and universally used as email.
Thing is, people who want to be found will use their real or well-known names. Those who don't, won't - no matter what rules a given service wants to impose.
XMPP was sabotaged by major IM participants not using it. Especially Google. They first were pushing XMPP a lot, but later betrayed the whole effort.