I should also add that it'd be quite easy to allow *opening* files with embedded NULs, I actually think it's just a matter of removing the check. However, it's likely a *lot* of features won't work right with the NULs, truncating some parts (and then, as @eht16 said it's totally fixable, but a lot of work and carefulness).

I think we discussed this in the past, and I myself wouldn't be against allowing to open those files read-only if it's something users want. However, I think others in the discussions were afraid people would still untick the read-only flag and start seeing bugs everywhere and complain, and that's probably a valid concern. We could possibly see what others would think could go wrong if we allowed opening read-only *and prevented those files from being made writable*, which would be a tad more work but probably fairly easy. Then again, how useful would be opening those if you can't modify them? I don't know.