First, let's address the easy answer to that question. It should be no surprise that hats attract the creative, "downtown" element. Having said that, I find it rather ironic that the brimmed hat - the sartorial marker of conformity in the 19th and early 20th century bar none - has now morphed into its perfect opposite, an individual choice of artists, musicians and entertainers. The recent surge of fedora and hatwearing is arguably due to the raffish element that hats give off today. A whiff of insouciance, of the dégagé and louche. This is true for both sexes. It's a unisex token of cool. For certain individuals, wearing a brimmed hat sends a signal of being unplugged as it were from the grid of conformity around them.
In addition to the fashion-oriented creatives, we cannot ignore the other distinct camp of hatwearers today: the retro-conformists. This group is all about the Restoration of rules established and practiced to perfection sometime in the 1930s and 1940s (i.e. see The Fedora Lounge). Like the creatives, the retro-conformists borrow clothing and accessories from a previous era. But unlike the creatives, the borrowing is done in conscious homage to a lost world of superior manners and etiquette, of clearly defined masculine and feminine codes.
Going back to the hats themselves, the essential difference between the retros and the creatives is the brim and crown. This recent Wall Street Journal article on the current hat craze is right about the utter domination of the stingy brim among the creative set. But the article falls prey to the myth that hats underwent a complete and total mass extinction in the 1960s only to be resurrected by fashion designers circa 2005.
Take a look at this 1985 video of a live, acoustic performance by Mike Oldfield performing his single "Moonlight Shadow". The vocals by Maggie Reilly are simply phenomenal, ethereal by the way. But let's go back to Oldfield's hat. On the one hand, it has a smallish, tapered crown quite unlike the tall, full crown favored by the retro-conformists. On the other hand, the brim is quite generous, longer than the short, stingy brim currently in vogue among the creative set. The point is that Oldfield wears a hat to fit his situation, whether performing in Manhattan circa 2009 or in Europe some 25 years ago. This is the logic of cool, not Restoration.
In addition to the two camps above, there's another category of hat wearers - the utilitarians. In a recent New York Times article, hatter Bruno Lacorazza says, “People always use hats. It’s a necessity, like food.” It's certainly a necessity when the sun is beating down or during inclement weather.
As a leading hat purveyor to the hasidim, Lacorazza also points to a fourth category - the institutional and/or religious impetus to wear hats. The hasidic community are among the most devoted hatwearers today for very compelling reasons of their own.
So there you have it - what's your reason to don a hat?