Popular arts are arts suited to the tastes, needs, educational levels etc. of the ordinary people. Highbrow arts are those considered to be of highly cultivated tastes and skills superior to that of the common people. A highbrow song finds few singers, because its range and technique are beyond the reach of most people. A pop song, on the other hand, is less in range and technique; therefore, everyone can sing it.
Schopenhauer's famous words "Man is either vulgar or lonely" contains different connotations. You may read it as to be yourself and not follow the crowd. You may read it as not to be so aloof as to become a loner. You may read it as to suit both refined and popular tastes and avoid extremism. As far as tango is concerned, I believe the last take is the most wise because, as a Chinese saying goes, "Water too clear has no fish, man too high standard has no follower." If you are too elitist, there will be few partners for you. Schopenhauer's words, therefore, can be read as a warning.