When someone says modern art, I often consider things like–
Piet Mondrian / De Stijl movement
–which questions the skill level required to be popular.
I understand where the mockery comes from, but there is a double standard to address.
The typical complaint relates to a common ability to reproduce an expensive painting with recognizable features. To summarize, a child can do it, what’s the difference?
If a child can play a Taylor Swift or Justin Bieber, etc. song, why are they not equally famous? The reasons you are considering are likely applicable to the previous art situation.
Let’s be honest, painting an orange square (Mark Rothko) is quite comparable to a drum beat pounding every quarter-note (Electronic Dance Music).
However, there is one key difference between the visual and auditory forms. When an artist blatantly copies an image, it is obvious to anyone with vision. When a musician openly copies a chord progression, it is commonly masked by lyrics.
There are artists determined to make paint look like a photograph, and musicians striving for complexities that are yet to be performed.
Still, simplicity remains more popular.