Because it's loved by Sony just as much as the PSP, right?
That's because the PSP thread doubles as the Vita thread.
I just realized something: we've had a 3DS thread long before the 3DS was even out, but the VITA is out right now and we still don't have a thread for it.
Plus , personally I think it probably works better if we just use the same thread for both. Rename it the "Sony Portable Thread"