a) Japanese gamers mostly play handheld games over console games. This is why PS3/Wii/360 combined in Japan make only about half the sales Wii or 360 alone make in North America.
b) Nintendo has been ignoring North America. Japan has a dozen colours of 3DS XL, until recently you could only buy a blue or red two tone console. I'm getting a black one, but I'd still largely prefer solid white.
Plus a lot of non Nintendo games are just taking their sweet time localizing. No confirmed Dragon Quest VII or Monster Hunter 4 localization, Bravery Default will be a year and a half old by the time it gets here, and a lot of games are consistantly releasing 9 months or so earlier in Japan then NA. 9 months is a bit much.