"That's the thing about overly casual dressing. It says: 'I don't give a rat's ass about anything.'"
ADDED: Here in Madison, Wisconsin, in the UW campus area, the young women are out-and-proud with the leggings-as-pants look. Nobody seems to remember the old days when you at least felt that you needed some kind of tunic-length top. The full length of legging is exposed, exactly as if leggings were pants. There's no reticence, no sense that this is out there or daring or maybe it's okay if the leggings are really thick and there's some sort of stitched-on pocket-and-placket imagery. I am seeing full-on Leggings Are Pants true believers.