When you run the headphone cord from your iPod/iPhone up under your clothes. It only takes two seconds to run the cord under your shirt, and then you don't have to worry about getting the cord caught on your car door, the counter top, or the vacuum cleaner (cause you know you listen to music when you vacuum). In addition, hardwiring allows you to let your earphones dangle just outside of your shirt (if you're really smart you'll even have two shirts on, and you can hide your earphones when not in use).
Becky: "Tom, why do you look so cool?!?"
Tom: "It's because I hardwire my headphones . . . see, no cord. It's called Hardwired headphones."
Becky: "OMG!!! That's like soooo smart!! I would've never thought to do something like that. I'm always getting my cord caught on my car door and my vacuum cleaner."
Tom: "Well Becky, that's because you're a dumb skank."