Actually, it's Sony.

Xenogears was made by Square, Xenosaga is Monolithsoft and Namco.

You can see it's the fault of Sony, because the Namco produced games Tales of Symphonia and Baten Kaitos were released on the Gamecube, ESPECIALLY Baten Kaitos since it's not even that big or popular a game, yet it was still released.

The PS2 version of ToS on the other hand was never released outside Japan, and the Xenosaga games were never brough to Europe.