There were a number of factors however primarily these:
1.) It was a JRPG on a system whose primary audience is still heavily for shooters like Halo 3 and Gears of War in the West. Also it was a science-fiction type of game being released at virtually the same time as a game in a more popular Western sci-fi series.
2.) The Japanese are showing that they absolutely refuse to fully get behind a system that they consider to be a Western console when they have viable Japanese alternatives even when the game on that system is an exclusive from a highly regarded Japanese developer. They are hoping SO4 will come to PS3 so they will be able to buy it.
3.) Its review scores weren't high enough. If it had had scores in the 9s instead of in the 8s and if its two leade in games had had good rather than terrible review scores, then they would have built up the momentum for it to have great sales in the West.
Heavens to Murgatoids.
