Most tasks we use computers for are deterministic and was coded for that specific quality. Introducing nom deterministic behavior is lowering the value of the app, especially for power users.
I don't think this is true. Computers are still computers, and code executes (mostly) deterministically. What computers struggle with is making sense of unclear inputs, precisely because of their determinism. OCR, speech-to-text, and computer vision all proved extremely limited when tackled purely deterministically. The whole "ML revolution" before LLMs was about recognizing that messy, noisy data can be interpreted with some accuracy using statistical methods. LLMs are the continuation of that: they are even harder to measure and completely impossible to prove, but they bring capabilities we have been unable to achieve any other way for decades. Should they be used to handle deterministic logic? No, obviously not - but they do enable computer systems to start working in contexts where they either couldn't at all before, or were just bad at them.