Sony HAS done well in Japan, have you not noticed the PSP being the number one, or at worst number 2, selling system there for months? I bet before its over the PSP will have come close to PS2 sales unless its replaced in the near future.
As far as the PS3 goes it is mainly a question of 360 moneyhatting to get JRPGs. Luckily, money has only bought timed exclusives it seems since the 360 isn't really driving sales. The 360s failures in Japan are what leads Eternal Sonata and other 360 "exclusives" down to path to "also on the PS3". In another year or 2 it will become quite apparent that the 360 is another Xbox brand also ran in Japan. Notice they are at 1/4th PS3 sales despite being out first and 1/10th Wii sales, if anyone has a success outside the US problem its Microsoft.
PSN ID: ChosenOne feel free to add me