Do you want to go back to codepages and needing to know the difference between CP1252 and ISO 8859-1?
Unicode should have been confined strictly to document content and UI presentation.
Oh but it would make file names less complex. We can't have that.
Edit: btw, how many ways can you express an "ă" in Unicode? How many different file names that look the same visually can you end up with?
Just like with ipv4 and ipv6.