Agree 100% with all points. I love contract-first. Better for producers and provides multiple tooling options and better docs for consumers.
I was agreeing with parent that some spec formats frankly suck to write by hand and openapi yaml is IMHO one of those (as opposed to say .protos which are nice for humans to read/write).
I use LLM as glorified interactive autocomplete to speed up writing the yaml specs (not the code! Use deterministic generators for that!) and it works great for me, personally (n=1 anecdote).
And more accurate than LLMs.
Feels like whenever an LLMs could code it, you'd be better of not having the boilerplate code at all.