People will be able to discern who is who based on avatars, merit count, merit history, signature, rank, and probably other things. The point is a random username won't do much if people can still find out who is who IMO. You would need to randomize everything.
Randomizing everything will be difficult to the scripter and also the forum users. It is impossible to anonymize a username such that no one will track the identity behind it.
The best to do is to create an alt for the purpose of discussing topics you don't want to be linked to your profile.