I guess the Anime Fandom for Japan and other places are very different.....like LenMiyata said, other animes that became popular in the US were actually cancelled or did poorly in Japan. So I think what some anime companies are doing is trying out the animes that did poorly in Japan to other markets like the US.
Anime is not new to US, but somehow only the ones that did poorly in Japan are the ones getting very popular in US. I mean I like Shinichiro Watenabe's Cowboy Bebop.....but I don't think this anime did good in Japan. To me, it all depends on content, exposure, and how close the anime is to the original manga.
Maybe Esthered is right, perhaps the people in Japan that loves anime might have been overexposed and has become picky or tired of seeing animes based in samurai, ninja, or what not!