That's a whole 'nother thread, by the way.
It's "Art for Art's Sake" season down here. I do love my artist friends but feel I offended one of them the other day with repeated heavy sighs as he extolled the Moments his little coterie had during their little readings together that morning.
While there's some truth to beauty's being in the eye of the beholder, I think that truth speaks more to Mind over Matter. The Golden Ratio (and a stretch of 6% on the average model's frame where possible) still is going to rule the day and we all know it. I mean, look how nicely the gay male and buff female flat-bellied aesthetics are taking hold of the collective consciousness. You see it all the time here on the forum, even.
Rather, I think the point of modern art was to destroy the math: no golden ratios. Destroy the natural relationships: no harmonic hues, even. And, above all, instill the idea that truth is relative and the days of extolling (by copying) the order and beauty of creation onto the page were LONG GONE ... along with signing "All for the greater honor and glory of God" instead of one's own name.
Rather, I think the point of modern art was to destroy the math: no golden ratios.
Take a gander, one of many analyses of mathematics in modern art. If you don't know about fractals, they are closely related to Fibonacci series and the golden section.
You're right, though, that nonrepresentation is stated by artists and theorists as a desirable characteristic of much modern art. But are they really painting what Tommy (without the sense of smell) would paint?
I will throw you this other bone; the vanishing point perspective (representing far away objects by making them smaller and blurrier) was not used in Western art until the Renaissance. I'm guessing you didn't take basic calculus (perhaps calculus took you), but it is primarily the measure (reducing to a number or equation) of space (integral calculus) and how fast that space is changing (differential calculus). So both math and art developed an atomistic view of space at about the same time. Is this atomistic view natural? Try looking at a lamp, and moving back two paces. How do you know, (visually, not intellectually), that the lamp is farther away? It's not because the lamp is smaller, although it is, a little. It's because you have a greater sense of space between yourself and the lamp. Consider which perspective would be more valuable to a hunter, trying to "cut off the ring" on a faster animal.
Reading this post is probably the equivalent of a weekend barbershop quartet festival, so I will close with this hypothesis: it's not the communists, or anyone else with a face (as we say at PETA), that's changing the world. They may be at the front of the wave, but the wave is the important thing.