I mean also, nativley, like md3 or Milkshape (milkshape has bones, but no weights) There is no native (I mean, included supported in stable releases) bones and weights format. Md3 has the problem (like *.3ds) that whenever a vertex has 2 UVs, the mesh is broken there, and a smoothing seam appears, is a format limitation. (besides the no more than 8,000 tris limit, and often accuracy in vertices position of exported mesh, by many exporters ) .That and bone based formats allow way lower file size for medium/large animations.
I know I have said it, but it'd definitely attract more artists.
They're the two more extended format in our tools , by far.