Black has often been the uniform of the "alternative" set and a symbol of rebellion since the '50's.
I'm being partially tongue-in-cheek here....there's a certain coolness about Johnny Cash. Why did Johnny Cash wear black?
In his own words, from the song Man in Black:
“I wear the black for the poor and the beaten down, livin' in the hopeless, hungry side of town, I wear it for the prisoner who has long paid for his crime, but is there because he's a victim of the times.
We’re doin’ mighty fine I do suppose, in our streak-o’-lightning cars and fancy clothes/ But just so we’re reminded of the ones who are held back, up front there ought to be a man in black.”
It’s been reported that Cash wore a black shirt at his first performance at a Memphis church because he wanted to look “smart,” and that he continued to wear black for good luck in every performance after.
Later, the Man in Black had this to say about his apparel:
“I wore black because I liked it. I still do, and wearing it still means something to me. It’s still my symbol of rebellion - against a stagnant status quo, against our hypocritical houses of God, against people whose minds are closed to others’ ideas.”