However, it is NOT the case that, given the circumstances under which we listen to music--brief, out of context, digital--that easily-digestible pop music will inevitably triumph, just because it is most convenient. Granted, one can hardly listen to Wagner on the subway, but I propose the following:
Following my argument, there would be two types of music: accessible (we'll say) and inaccessible. Under the former category, all "hits" and forms of pop music. Basically, what one could play in an H&M. And in the latter category, cerebral and difficult music, that requires spending time with, etc.
But here is the important part: once you have assimilated, memorized, accustomed yourself to a piece of difficult music (or a fairly uniform genre), that music BECOMES accessible. The experience of listening to something already "processed" is separated by an abyss from the experience of unfamiliar ears.
Even the most abrasive, complicated, or retarded music, once it is entirely-expected, might as well be pop music.
I can imagine some exceptions to this: a perennially-difficult work or group, unable to be completely assimilated..... as well as a series of assimilations and rediscoveries of a single work in the course of a lifetime of listening, but those are separate topics.