> "Most people are just looking for some simple thrills"

This is patently untrue. Two of the top films in theaters right now are Interstellar and Gone Girl, neither of which can reasonably fit under the umbrella of "simple thrills". In fact Gone Girl has been widely described as a very difficult film to watch in terms of its emotional impact on its audience - suffice it to say the appreciation of that film goes above and beyond mere entertainment, yet both are "popular art" in the sense that they are widely consumed by the mainstream.

The general public is capable of a substantial amount of artistic understanding, and there are more experts out there than you acknowledge. Appreciation of different types, genres, and subgenres of art change over time as a reflection of culture.

One good modern example of this is the comic book movie - comic books have unique thematic, structural, and aesthetic elements to them that were previously the exclusive territory of comic book nerds. In recent years this has gone spectacularly mainstream - and hundreds of millions of people now better understand stuff that used to be pretty inscrutable.

All art exist in a spectrum between the novice and the expert, mainstream society is quite expert at some (see: music, cinema) but not currently practiced in others (see: postmodernism). To boil the artistic sensibilities of the mainstream down to "simple thrills" is not only grossly cynical, it's grossly incorrect.

"Popular art" is not mere entertainment - and it has never been, and has always been a reflection of the time and place in which it's created. Captain America - popular right now - was a nationalistic symbol created during the midst of WW2 when it was felt that such a symbol be needed. The utopian portrayal of the future in the original Star Trek attracted viewers as an optimistic opposite to the Cold War. Heck, the conflict between the Federation and the Klingons is a direct analogy between the USA and the USSR (and naturally, the Federation always prevails).

And these art forms evolve - just this year we've had two massively profitable films between the X-Men and Captain America where the US government was portrayed as openly malevolent, and one of them directly addressed governmental spying. These works transparently reflect the times in which they were made. With the increasing media attention on drone strikes worldwide, even the RoboCop remake wasn't spared - the movie went from a reflection of 1980s crime anxiety to a reflection of 2010s morality re: drone strikes.

This isn't just movies either - Tupac built a huge mainstream career and long-standing legacy on works that plainly and openly commented on crime, race, and equality in the context of 1990s America. He's far from the only one - the general public is much more capable of expert artistic appreciation than you give them credit.

People seek commentary, understanding, belonging, and even escape from the world and times in which they live, and popular art has provided this, and in this way they are not substitutable. The notion that people can or should subsist on past art exclusively is plainly false, as is the basis assumption that "popular art" is merely entertainment.