Thing is, I might actually support such regulation. And before you call me crazy, hear me out after the break.
While living in New York, I was wearing a set of headphones while walking near a busy intersection. I was crossing a street with the walk signal when a car came barreling down the street — I didn't hear it because of my headphones. A man walking behind me pushed me out of the way of the car, which ran the red light (thankfully not hitting anyone or anything).
So while I see the case against regulating the use of headphones on the street, I'm also personally invested in the fact that, even if you are paying attention to traffic signals, not being able to hear your surroundings can be equally as dangerous. But is it not enough to rely on individuals' good judgment? Do we really need a law to tell us?