Art is subjective, but for me being in a museum and going from Impressionism and post impressionism, and into a modern and post modern gallery is like a slap in the face.
In my experience, all I feel is it goes from beautiful paintings with high skill level used by artists to visually manipulate form and shape to create coherent but stylized images, to "check out this crushed oil drum, really makes you think huh?"
Really gives the impression of that feeling you get when a school project is due soon but you have no idea what to do and don't particularly care to do it but know you have to do something if you don't want to get a 0.
I think what you dislike is bad or low effort art, not post modernism. Just because piece of art denies the canon, or the classics, doesn't necessarily mean it must eschew beauty, or be made without technical skill.
Apologies to anyone who knows their art history - I'm speaking in broad strokes here.
Personally, my beef is not only the low skill/effort a lot of the post modernism sculptures have, but also that their whole point, of making fun of "high art", of museums and whatnot, was subverted. The subversion of art was subverted. Not even Banksy could fully escape the elitist assholes and even though that picture was shredded after the auction, it's still "valuable"
The top one looks like light coming through closed shades. Kind of makes me of how think about how many people see a similar view before they get out of bed.