I am seriously having problems in understanding this concept

This guy I get, he has long hair he needs something to hold it! Actually Jared Leto is gorgeous (his normal version not his latest skinny version for  Dallas Buyers Club), and when I read last year about the sexiest man being Adam Levine, I just thought of this guy and what an injustice that was =P

But now please explain to me this trend in Hollywood men. What the hell is this? Seriously, I am not even gonna go into Harry Annoying Styles' bun and head band combo! This trend just seems silly to me...