Even if most of the code you write is solving repetitive plumbing tasks, today's models are incredibly bad at API design taste. IMO designing software in a way that minimizes side effects and is easy to change and test is more than 1% of software engineering.

Lately most of the code I write has been through LLMs and I find them an enormous productivity booster overall, but despite the benchmarks they're not expert human level quite yet, and they need a LOT of coaxing to produce production quality code.

As far as things LLMs are bad at, I think it's mainly the long tail. I'm not sure there's one singular thing that >1% of programmers work on that LLMs suck at, but I think there are thousands of different weird sub-specialties that almost no one is working on and very little public code exists for, thus LLMs are not good at them yet.

Try using any AI tool to write a working realtime GI (global illumination) implementation. I've been working on a novel implementation for 60fps/1080p GI and everytime I use Copilot or Claude to even try fixing a minor bug/troubleshoot it nukes entire functions and rewrites them using garbled shader code, old syntax/methods.

Puts things into stark perspective for me.

PS. no amount of prompt engineering will save you in this endeavour.