I think what's kinda wild to me is how the older mid-late 20th century generation of SF writers were just so capable. I mean, Harry Harrison wasn't someone you'd praise for raw skill, but he was able to effectively entertain with all his pulp and satire. Hell, "Make Room, Make Room!" became Soylent Green (the film) and that's been kind of a famous dystopian future movie. What just keeps me enjoying that long stretch of sci-fi from the 20th century is the sheer variety. There's something for every mood, every variation, every level of read one could want. Want pessimistic speculation on the future? John Brunner's there. Want something classic with lots of puzzle/mystery elements? Asimov exists. Want something written by a philosopher that wanted to explore grand ideas and philosophy through sci-fi? Olaf Stapledon's still heralded as the bar to beat. God knows there's all sorts of subgenres from Time Travel, Alt-history, Sword and Planet, Space Opera, Military SF, Anthropological SF, and so on.
Modern science fiction seems to be limited to like, maybe a dozen competent writers that are active. All of which seem to be in their 50s or older.