It's a great game and deserves It's sale. PS3 still has heavy JRPG roots it JRPGs will always sell better on the PS3.
WRPGS are a different story. Fallout 3 sold a million + better on the 360. I would mention Oblivion to but It's not too fair considering how late it came out.
*Captain Obvious to the rescue*
It's just that simple.