To be honest, I disagree. Unix filenames are printable text, they're just text that the OS chooses not to enforce any validation on. Especially since the charset is implied by your choice of locale, which is a user decision, not a kernel decision. But we've transitioned into a world where pretty much all systems have settled on UTF-8 as the charset of choice, and the OS's refusal to even permit kernel options to forcibly validate filenames as UTF-8 is starting to look like a poor decision.

(IIRC, at least one of the BSDs has actually moved to forcing filenames to be UTF-8 and refusing path names that aren't UTF-8. Would only that Linux moved down that path as well so that we could be done with this farce.)