The game is region locked because they are probably doing a server rollout on a continental basis so as not to overwhelm an untested system. From what I have heard, not a great deal of stress testing going on.
Doubt it will be region locked, apparently they've got "megaservers" that decide where you play automatically and in which pool. As for why it can't be ordered outside, no idea, perhaps its a limitation by the publisher Amazon has to adhere to. Try Gamestop, they seem to have it as well.
I meant the release is region locked, sorry. They are most likely doing a limited release rollout one region at a time. I am a former employee of a company that makes MMOs and I can tell you from first hand experience that a world wide launch is a horrible idea, anything and everything that can go wrong will and it is best to release the game in stages to combat bugs missed in beta... especially when you barely beta the game. My company did the same thing and what we thought was a release quality game was plagued by bugs, server downtime, and an angry playerbase.