I think even with the best GUI (and I seldom have seen worse GUIs than with GIS tools), scripting is way more powerful, if you have advanced tasks.
Definitely more powerful but well crafted GUIs can enforce constraints on inputs and preview what changes would look like.
Agree that I have never seen a GIS tool where I thought the GUI was top notch.
Answering my own question somewhat, I think that LLMs are becoming a kind UI layer over many applications/tools for many users. Which is interesting. And in some ways they show signs of fulfilling the promise of AI.