Simply because the 360 started off as having terrible hardware which did not help improve the Xbox name in Japan. On top of the terrible hardware it was known as being a shooter box but since the JRPG have released on the console it has sold well. Saying Japan hate American products and will always choose Japanese products is a silly thing to say, especially with how the iPod is doing.
Put the games Japanese people want on the 360 and people will purchase the console.......simples!
Edit - Hiroshima and Nagasaki? That is about as tasteless as it gets, really stupid stuff.







