I'm confused by that as well. I never really understood the motivation behind it - though I guess it's obsolescent, so hopefully it'll soon be just another one of those amusing anachronisms we see occasionally in computer science.
As I understand it, the motivation was to be able to transmit Unicode text over a channel that's only 7-bit safe (e.g. mail protocols) without having to do something silly like Base64-encoding the whole thing.
