Part of it is branding, to be sure. But in Pitchfork's Resonant Frequency column, Mark Richardson rails not against the quality of the Beats line of headphones and its signature, overloaded bass, but rather argues that they're a viable alternative for a new era of music.
Richardson's main issue with audiophile logic—and something that I whole-heartedly agree with—is that they don't take into consideration modern music production (synthesizers, edits, overdubs, etc.) when evaluating headphones, but mostly rely on classical audio as the reference audio source for speakers and headphones. Reading between the lines, it seems Richardson also argues that audiophiles aren't as concerned with the music as they are in accurately reproducing sound for the sake of accurately reproducing sound.
We live in a time when everything can be tuned to individual preference. The entire concept of subjectivity is arguably embraced more now than in any other era. This platonic ideal of ideal forms, whether it be audio, visual or otherwise, is not a concern for many people today. (Hell, look at Instagram)
But to drive his point home about someone who disliked a pair of Sennheisers for their lack of bass, he drops this particularly well-put paragraph.
Beats by Dr. Dre are popular because they don't reproduce music as much as they transform it. They are the right headphones for the current era, because their design "customizes" the sound for the listener who wants bass. Music is never finished; we can chop and screw, add bass, slow it down 100x, mash it up with something else. And people will buy headphones that finish the music in the way they like.
It may not be your sound, but it's not necessarily a wrong sound. [Pitchfork]