> historically we didn’t have LLMs which don’t mind “unpleasant[ness]” and “heavy rework”.

I'm not quite as optimistic. "Unpleasantness" might sound like subjective disgust, but it often relates to objective criteria like complexity, that increases the surface area open to bugs in a real way. Similarly, if reworking has a non-0 chance of bugs, its gonna have some form of risk, and a major one will of course be higher.

LLMs may be capable of a lot, and they miggt change what projects people can take on, but they definitely don't write bug free code.

The bun rewrite/transpile did use some neat ideas like lots of testing and per-file translations, so hopefully they have more in their toolbox than "LLMs hopefully won't be affected by complexity or write bugs"