The Java and .NET infrastructures make that choice for you too. I guess I wasn't there when Java first got started, it's possible that there was a backlash[1] against this decision by the people who are using encodings that aren't subsets of unicode. I don't get to see many "enterprise" systems, but I get the impression those applications where it's important to use some kind of not-unicode are sufficiently rare that they're best served by specialty libraries. You can't make everyone happy with one solution, but if a simple solution works for 99%, then I'd call that a roaring success.

[1] a backlash other than the OMG-2-bytes-per-ASCII-character hysteria, which is irrelevant for these purposes, they could just as well have chosen UTF-8