The reality i believe is they probably want less of a workload when the thing launches, because it will probably be full of bugs at launch, and dealing with a 3rd version is only going to hamper the speed at which they can make updates. They probably did secure an exclusivity agreement with sony too, why wouldn't they, for obvious reasons - less final fantasy fan base on 360, not everyone has enough room on hdd or a hdd at all, and paying xbox live fees and this makes it less appealing. They did mention it was microsoft's network policy, which i would assume means Microsoft was trying to take more of a cut on subscription fees by forcing it through xbox live, they may have let the fees slide on FFXI because apparently they paid for the port for it to the 360, but didn't want to this time around.
