I don't think it's fair to conflate "having structure" with "being formulaic".
Even the most abstract art is not about splashing paint in a canvas and calling it a day. It's about doing something close to this, but creatively and within a specific framework.
It takes much more skill to produce songs with hooks and refrains than to produce random music.
But it takes even more skill to produce something that is creative, not formulaic, but still has some structure that's pleasant/fun/interesting/etc to the listener.
The second best art of this time will always remain "who's afraid of red, yellow and blue?" after it inspired such fear in someone that they sliced it up with a knife.
Even the most abstract art is not about splashing paint in a canvas and calling it a day. It's about doing something close to this, but creatively and within a specific framework.
It takes much more skill to produce songs with hooks and refrains than to produce random music.
But it takes even more skill to produce something that is creative, not formulaic, but still has some structure that's pleasant/fun/interesting/etc to the listener.