Could part of it be because the left’s themes are simply easier to capture in art? I see a paradox where lefties — the elites, not the zombies — tend to be very well educated, very intelligent, very creative, yet the left’s ideas are in general much simpler than those of conservatism/classical liberalism. Take economics, where leftwingers basically want a centrally run command economy. This is pure simplicity compared to the Austrian model which understands deeper and subtler things like distributed intelligence and spontaneous order. And then the question is, which of these models would be easier to comment on or express artistically (assuming one wanted to do such a thing)? The first model clearly would be, because it’s simpler.
So maybe there’s more lefty art simply because lefty art is easier to pull off. Maybe it’s easier to do their themes proper justice artistically. Sort of like the reason there are piles of rock guitarists out there but relatively few jazz guitarists. Jazz is just a much more difficult genre. Almost anybody can improvise a pentatonic rock solo over some I-IV-V chords but almost nobody can play a good lead over complex jazz harmonies. Likewise almost anyone can riff on “social justice” but to flesh out the subleties of negative rights and that sort of thing? How would you capture that in graffiti? How would you write an angsty song defending equality of opportunity versus equality of outcome? Etc.
I have a feeling that leftist artists have an easier job and therefore can be more prolific, and by being more prolific can flood the zone and achieve a kind of dominance.
I recommend Tom Wolfe's, “The Painted Word”. He does an excellent job of explaining how certain artists become the “rock stars” of the art world. Fundamentally, which “artists” make it into the lofty world of wealthy fame is controlled by a handful of powerful critics and museum directors. People like Maplethorpe are literally “anointed” by the art world priesthood.
Two recent disappointments in our travels have been the University of Texas museum in Austin, and the Mesa, Arizona, city museum. Yes, it is possible for insulting to become trite, common, and unimaginative.