For the record, I don't 100% shame people who wear fedoras. There's a small handful of people (prominently the Bennett twins from Steam Powered Giraffe) who can pull it off.
The thing is, you can only pull off that kind of hat if you're a person who's already cool without it. It's like the guys I see who insist on walking around in a suit and tie constantly; I know one guy who insisted on attending Halloween Horror Nights multiple times last year in a full suit, tie, and fedora. They think they look cool and fancy and stylish, but they just end up looking terribly awkward because you can tell that they're doing it intentionally. You can't intentionally make yourself cool if you're not cool yourself. It's like putting lipstick on a pig, except instead of lipstick it's sunglasses.
I think the fedora became such a fad among wannabe cool guys because of its association with classy, old-timey gentlemen. Socially awkward asshole Nice Guys and loveshys who like to think of themselves as superior to the modern Alpha Males (TM) style themselves after 40s movie stars like Humphrey Bogart or "gangsters with class" like the romanticized view of the Mafia; they generally have a romanticized view of the past, thinking of it as an era where being a gentleman was more important than your physical perfection. So they wear fedoras and pinstripe suits and waistcoats to try and emulate that.
Of course, most of them are creatively bereft and probably not entirely in touch with reality. So instead of seeking out their own style or improving on themselves, they simply imitate the rest of the guys. So they all end up with identical clothing: fedora, trenchcoat, and sunglasses. Probably pinstripes for that extra bit of 40s class, leather fingerless gloves to seem tough, and a neckbeard because they don't care enough about physical appearance to groom properly.
I'm just sad that legitimately good and attractive fashion trends have been so thoroughly ruined by socially awkward, very loud assholes. It would have been better if they tried to emulate true chivalry and go about in full plate armor and/or chain mail that they can hang their mall katanas off of.