Of course it's for attention (or to repel attention, so they have an excuse for their singlehood other than "I'm repulsive"). It's not to rebel, it's not to make a statement, it's not artsy. It's not a "cultural norm" to dress in a way that attracts the opposite sex (or same sex if that's how you swing). If you want to be attractive, you need to make yourself attractive. That's just common sense, not some oppressive "societal norm".