The Japanese market is eccentric, compared to North America or Europe. There are many strange things that are liked there and no where else in the world.
However, to say it does not matter ignores the fact that if it were not for that market, there would be no other market. Videogames arose out of the ashes of the 1983 crash in Japan first. Had Nintendo not broken into North America in 1985, we'd all be playing our games only on these computers which we are using to argue about video game consoles and handhelds.
Japan will continue to be a source of unique and different ideas. Some will catch on in other places, many will not. But there are games unique to any market globally (e.g., How many copies of Madden are sold outside of North America?). And that's OK.
I you say history does not matter today, it is because of this history that many of the large game publishers are in Japan -- SquareEnix, BandiNamco, Techmo, etc. For the same reason, two of the three console makers are based there -- Nintendo and Sony.
Finally, that history also tells us that some things that were thought of as "weird and Japanese" became mainstream. RPGs anyone? That could be playing out again with more casual/short-play games and unique non-traditional games like WiiFit. (It may also point to the fact that Japan has an older population than either Europe or North America. So those playing are older and want different things than the typical US college student gamer).
So Japan does matter. It always has and will continue to do so for the foreseable future. It might be diferent, but it always has been.
Mike from Morgantown