But the "mainstreamity" (connecting a society and being a central cultural focus) is also a desirable attribute from music (from art in general), that is lacking today.

That is, there's music that's great but not mainstream and music that's mainstream but not great. The sixties and seventies (up to the nineties maybe) had both.

Modern good music has lost that, and everyone listens to good or even excellent music oblivious on his own little world and niche.

(Oh, and I'm not waxing because I'm some Beatles-loving older guy -- I'm much younger and in fact I listen to tons of new music most people wouldn't even touch, from Nobukazu Takemura to Mount Erie, Four Tet, etc.).

For me it's like great modern music is like some excellent Social Media site, with tons of features, great layout, speedy backends, nice UI et al, but where there are very few people using it. Yeah, in itself it might be a great web app, but where's the conversation and the social aspect?