They are so bad at UI. I'm not a traditionally trained UI dev, but in the past I've been the solo dev on so many projects that I had to git gud on making at least a clean, functional UI. No crazy animations and "delightful experiences," but I'm skeptical that level of design is necessary for anything outside of consumer apps designed for kids and the child-like. My default, slapped-together UIs for just getting out of the way and getting forward movement are still infinitely better than the inconsistent, buggy, overly decorated UIs the LLMs produce.