PS2 controllers are easily supported with inexpensive adapters. Xbox 360 controllers use a newer interface standard than FFXI was programmed for. DirectX 8 and 9 do not support XInput, which the Xbox controller driver uses, they use DirectInput. SE doesn't write hardware drivers, they can't enable the controller, just the standard, but they would have to update FFXI to use a newer DirectX standard to support XInput. That would be an overhaul of the whole game to do so. PS3 controllers are even newer, and have similar support problems. The community has solved these problems already with custom drivers, and XInput to DirectInput translators.