PlayStation Network subscribers can't change their usernames, and they can't delete Trophies.
But why? Well, SCEA president and CEO Shawn Layden was asked this very question in a recent IGN interview and he says it's not a technical issue. Rather, it's about trolling prevention.
He did say that being able to change your PSN username and the ability to delete Trophies is planned for the future. But thus far, Sony has resisted due to…well, adolescent social reasons. Said Layden:
"We don't want to make it so that you can go in, grief a bunch of people in Far Cry, change your avatar, change your username, go into CoD and grief everybody over there. We want to stop that."
He admitted that it's not ideal that Sony has to make a policy decision based on bad behavior in the gaming community, but it remains a reality. "I hate that we have to do that," Layden added. At the same time, they want to give people the option without having a simple experience ruined by a few "bad actors."
Bet you didn't think this was the reason, huh? Personally, I really need the option to delete Trophies. Having reviewed so many games over the years, I've got a zillion Trophies for games I don't own (and games I don't even want people to know I played).