My theory on art is that modern "artists" realizing they can never equal or surpass the works of the ancient masters, had to redefine art to mean "whatever crap I am capable of producing". The same theory applies to classical music.
I disagree. There are undoubtedly plenty of artists who have the raw talent to do art of the same quality.
The difference is in their outlook: modern artists reflect our narcissistic culture.
I pretty much agree with you, but with a caveat. Much so-called "modern" art makes sense to those studying design. Certain colors mix well, certain shapes balance well, etc. Good design is not easy, even in modern art. There is method to the madness in well-designed modern art.
But yeah, the bulk of it is junk.