I am not saying rewrites are always warranted, but I think LLMs change the cost-benefit balance considerably.

I am with you on this. I'm very much not sure about rewrites, but LLMs do change the cost-benefit balance of refactorings considerably, for me. Both in a "they let me make a more informed decision about proceeding with the refactoring" and "they are faster at doing it than I am".

Jup. Claude develops the first 90% without a sweat, and then starts flailing.