I can understand why case-insensitivity wasn't done in early Unix (why bother doing it in the kernel when you can just establish a culture of avoiding capital letters), and I can understand why it wasn't done when Unix began to get popular (the IRC protocol treats '|' as identical to '\' in nick-names because they're different-cased letters in the Scandinavian equivalent of ASCII), and I can understand why it's not done today (the Unicode rules for case-equivalency are scary-complex).

It is a bit of a shame, though. Come to think of it, maybe we should blame the medieval monks who decided we should have two parallel alphabets of similar-but-not-identical symbols.