I think the problem is how accessible they are. Music like Taylor Swift's is easy to get into. Simple rhythms, simple lyrics, and traditional instruments. Compare that to something like Faust, or even an album like Loveless. Those aren't really something you can hop in the car with and listen to a couple of singles and just bob your head to. It took me a couple of times listening to those albums to really appreciate them. Katie Perry, and Justin Bieber are loved so much because they are easy to love.