So far as I can tell, generative AI coding tools make the easy part of the job go faster, without helping with the hard part of the job - in fact, possibly making it harder. Coding just doesn't take that much time, and I don't need help doing it. You could make my coding output 100x faster without materially changing my overall productivity, so I simply don't bother to optimize there.
No software engineer needs any help if they keep working in the same stack and problem domain that they already know front to back after a few years doing the same thing. They wouldn't need any coding tool even. But that a pretty useless thing to say. To each their own.
I’m not sure I follow the question. I think of plumbing as being the exact kind of verbose boilerplate that LLM’s are quite good at automating.
In contrast, when I’m trying to do something truly novel, I might spend days with a pen and paper working out exactly what I want to do and maybe under an hour coding up the core logic.
On the latter type of work, I find LLM’s to be high variance with mostly negative ROI. I could probably improve the ROI by developing a better sense of what they are and aren’t good at, but of course that itself is rapidly changing!