I like the en dash, but I'll admit that it doesn't serve a real purpose that couldn't be served by a hyphen. I guess you could argue that there's a difference between a hyphen as a separator (as in a phone number) and an en dash as an indicator of an inclusive range, but there's no real risk of ambiguity.
I still think em dashes and hyphens should be separate, though. Using single hyphens for dashes leads to confusion because you can't tell the difference between a compound word and a break in the sentence, which are very different things.