The AI spreadsheet example in the linked article is interesting, but that occurs within a more specialized and constrained environment than general GUI design. I think of good UI design as involving a lot of human factors understanding combined with 2D spatial reasoning and layout, which I don't think AI is good at. (Today's article about Claude failing to reproduce an HTML layout to match a screen capture is one example of this: https://news.ycombinator.com/item?id=46183294 )

But my pessimism may be unfounded or based on ignorance. At some point AI will probably get better at these things as well, either with better LLMs or by augmenting LLMs with outboard spatial reasoning modules that they can interact with.