The filesystem can't be responsible for displaying anything, though. Displaying filenames is the job of the shell / window manager / etc.
The filesystem is much better off handling filenames as a number of arbitrary bytes. Let people who want to put weird bytes in their filenames see ugly filenames along the lines of "\x00 Can you see this?"
Or worse, you speak multiple languages, or learn new ones, and need to... switch codesets? How do you then access your old files?!
We must switch to Unicode. Full stop. If there are imperfections in Unicode script support, then we must fix those, but otherwise we must adopt Unicode.
The filesystem is much better off handling filenames as a number of arbitrary bytes. Let people who want to put weird bytes in their filenames see ugly filenames along the lines of "\x00 Can you see this?"