I get your point but disagree strongly. One topic that's been on my mind a lot is durability. The culture of LLMs is that everything is transitory. Why bother keeping a vibe coded codebase around for more than a few weeks, when the next big model iteration will be able to vibe code it better?

By contrast, free software in general, and Rust very much in particular, has cultural norms that things should last a while, rather than immediately being thrown away. I think that's worth preserving.

You can marshal values, but you can't marshal lifetimes, ownership, (lack of) thread-safety, (lack of) side-effects, etc. The ABI carries far less information than the Rust compiler relies on. Thus, any FFI call is inherently unsafe. It takes you, the programmer, with knowledge the compiler doesn't have and the architecture doesn't provide, to determine whether the code as you use it actually is safe or not.

because they change the binary layout sometimes, and the benefits have not yet been judged to be worth freezing it.

It is explained elsewhere, but a summary is that any language with generics is going to have any stable abi as a subset of the language. There is already a subset of the language that is a stable abi, it is the c abi. Expanding that subset has to be worth it in terms of what people actually want to export from a library. As I use generics fairly heavily I don't think I would use that expanded abi for anything.