Why does the psp have the og stick on the left side?

It just seems a a perfectly logical thing to do to put it on the right side for FPS's or better camera control in 3d platformers. every single pc game works with wasd for movement and mouse for looking, all fps in the DS have this scheme as well. heheh i'm just very confused why sony didn't place the og on the right side on its newest portable PSPgo. maybe is just my preference or is there some kind of limitation that impedes the stick to be to the right side of the handheld?