^ I won't lie, Kumi has many very Western sounding hip-hop tracks, and Namie is just as bad with that genre, if not worse. And Hikaru..? She IS American--lived there for many years and obviously likes the culture--so whatever. But people like Ayumi, m-flo, every Visual-K band, SOUL'd OUT, hide, Gackt, pretty much any anime singer or techno pop star, and countless others... Nothing like the Western world. And many of those happen to be some of the biggest artists in J-Pop/rock/etc. history. Really, the only music that sounds Western in Japan, I think, are a lot of the hip-hop acts, and maybe some of the rock ones. Even those artists that do alternative type music or simple piano ballades, such as B'z or Chihiro Onitsuka, spice it up into something different from the Western equivalents, despite there not being much to do with such genres.
But at the end of the day, this is all just opinion. So I suppose it's another of those agree to disagree things, yes?