Honestly, I think pre-registration should be allowed. People are not online all the time so some people may not be able to get the username they want or get to play the first day it opens. For example, someone who is in college, such as myself, has a different schedule every day. I would hate having the game open and someone taking the username I want while I am in class, hanging out with friends, or just busy doing something else.This goes for people in high school and people who work as well.
I think that it would be nice if peoples usernames they use for the forums were "reserved" for a certain amount of time. This would mean that no one else can take that username for a certain amount of time (allowing you to claim the username so you can be the same user on the forums and in the game). If the username is not claimed after a certain amount of time it can be "unreserved" and up for grabs for anyone to use. The reason I think this would be a good idea is because it makes it easier to find people from the forums in the game.