> As a very very heavy LLM user, I also notice that projects tend to be much easier for LLMs (and humans alike) to work on when they use opinionated well-established frameworks.

i have the exact opposite experience. its far better to have llms start from scratch than use batteries that are just slightly the wrong shape... the llm will run circles and hallucinate nonexistent solutions.

that said, i have had a lot of success having llms write opinionated (my opinions) packages that are shaped in the way that llms like (very little indirection, breadcrumbs to follow for code paths etc), and then have the llm write its own documentation.