twesterm on 02 December 2008
It isn't Sony's choice for all of those games, it's the developers. Konami would have to want to bring the Metal Gear games to the PSN and they're still too busy making money off their PS2 collection to worry about that.
As for the FF games, FF 1-4 have all been recently remade completely for the DS and I imagine VI (not sure about V) will get the same treatment. Who knows where VII-XII will go.
