Countess, I don't particularly like bluegrass, either, but it's hardly "not rooted in tradition". Just because it's not that old doesn't mean it isn't ROOTED in tradition--it borrows very, very, heavily from both old-time and blues (which, by the way, is not that old, either, in its recognizable form). There is a lot of stylistic innovation but--and this takes into account, of course, that there are lots of styles within bluegrass, as well--there is a lot of crossover.

Why would it have to be rooted in a single tradition? A) it's all American. B) Most American music is not rooted in a single tradition. Blues sometimes borrows from old British ballads. Piedmont blues is a combination of blues and Appalachian music, to the point where it's often hard to tell if the musician is black or white. Old-time is descended from British and Irish traditions but is by no means the same thing, and later it appropriated ragtime and Tin Pan Alley elements without losing its identity (and both "Old Joe Clark" and some versions of "Liza Jane" are from African-American tradition).

I don't like modern bluegrass. I cannot stand Alison Krauss. I don't think she's bad, I just hate the style. If you're thinking of that kind of thing (or Nickel Creek, or whoever), I can see why you would think that if you don't listen to bluegrass. But it's much more obvious in earlier, less-commercialized bluegrass.

. . . and now that I've made a big fuss, yes, I agree we're all entitled to think what we want, but I don't see how having multiple roots from the same country disqualifies something as "world music".