I agree to the extent that "Rust will save us" is a glib answer, but dismissing it completely is equally silly – safe-by-default is an excellent tool to help prevent many of the common sort of vulnerabilities we see in C code.

I don't really agree with the rest. "Simple file formats" is a theoretically nice idea which is impractical – after all, features are added to file formats for a reason. "Restrictive not permissive" is, as others have pointed out, a divergence from the generally useful Postel's law. Writing a library which cannot handle common problems in file formats – of which there are a huge number, due to sloppy implementation – is a good way to ensure you have developed a library which will be used by few.