The Left postmodern view of beauty is just like their position on morality, that it is a social construction, is not objective, and in art, even a jug of urine can classify as art; anything goes, so long as it is politically correct. In fact, my son went by a small modern art centre, with weird structures out the front. A woman was assembling some monstrosity. Trolling her, he said that he was a postmodern artist working with rusty corrugated iron, which he used to symbolise Western racist culture. She was immediately interested.
The conservative position on beauty sees beauty as intrinsically connected with the good, just and the true, with that which is noble and holy, and thus having a religious aspect, which is why in ages now gone, fine art was a product of religious sentiment and expressed religious themes.