Over 16 million consoles have been sold in the region this generation. Only one other single country has a larger install base than that, and its America. Further, if you count handhelds, it is well over 60 million total hardware in the region. Now if 60 million is no longer a factor, then everything but America isn't a factor haha. Japan is still a vibrant market in both the hardware and software markets. Although the growth in the American and mainly European markets seem to be overshadowing it, it's not like Japan no longer is worthwhile.
I think a lot if just has to deal with that lack of growth because it's already a well-established gaming country, more so than any other country in the world. So as everything else gets bigger, it is really hard for it to grow in comparison. But doesn't mean it isn't still a big market which it is. I mean let's not forget that the biggest release in the entire UK was MW2 which has done about 3.1-3.2 million (not sure if it is still behind Brain Training or not thought), which New Super Mario Bros Wii has destroyed in no time whatsoever and that isn't even close to its highest potential sales. Point is, the people there are heavily game oriented and when you release the right game, they'll eat it up at larger percentages to userbase than any other terrirtory.
