If they let us start changing servers you'd have a small handful of overpopulated servers and the rest would be completely empty. How does that look for PS3 and/or new players starting the game? They'd want to get into a populated server but instead their options are "not getting into the over populated servers" or "Colonize a dead server".

Personally if I were SE I'd wait until after the PS3 population stabilizes to allow any kind of server transfers and/or merges.