We've seen articles on this wannabe-happening over the past several years, but let's take a little time to dissect it. I'm judging from this slideshow of pictures.
First, it's clearly in a dying stage. The participants by now are a lot uglier, more people-ignoring, and SJW-ier (but I repeat myself).
The event began in the mid-to-late 2000s, when there was a more slightly more outgoing and fun-loving social climate. The participants were mostly attractive hipsters, the type who would have gone out to '80s night wearing American Apparel shorts. They cleared a bare minimum of fun-loving-ness and comfort in their own body.
Sometime in the past five years, it must have attracted the attention of the Slutwalk crowd. By now, they are the majority in pictures. They don't go out dancing, they feel awkward in their bodies (not surprising given how doughy are), and they aren't doing it as an ironic goof but as an overly serious pseudo-provocation. They're too busy staring down at digital screens or the blank pages of their Moleskine journal to make eye contact with the by-standers. And you can't be a public instigator without making eye contact with the crowd.
It doesn't seem like generational turnover, since the early-to-mid 20-somethings five years ago were still Millennials. In fact, the whole thing feels like a semi-risque slumber party of the type that might have taken place among high schoolers and college kids, back when they actually threw parties (a small get-together where everyone stares at phones or passively watches beer pong is not "throwing a party").
It's like the Millennials are trying to have some of the fun they were denied by growing up with helicopter parents and in an overall cocooning environment. But acting like a high schooler at your first party when you're actually 25 just makes you look more awkward. That ship has sailed, so you might as well try to have fun in a more mature way like going out dancing instead of showing up in public in your "undies" (as the kiddie generation refers to panties). In one picture, those "undies" are further infantilized by having a great big "Harry Potter" logo across the back.
But the infantilization gets worse: this year's event shows several parents who are participating with their children. One mother is even wearing one of those kiddie animal-head beanies with the long braids down the sides. In our stunted era, being a "cool mom" doesn't mean going out dancing at the disco, but dressing up like a kid for a kiddie no-pants subway ride.
Aside from Jerusalem, the Washington DC area has the ugliest young people of any major city. It has nothing to offer people whose orientation is more corporeal than cerebral, so it only attracts out-of-shape misfits who obsess over policy details. Say what you want about where New York has been heading, but there are still some things to do there, and it still manages to attract halfway attractive people.
In the New York of a few decades ago, though, nobody would have behaved this way -- throngs of nubile girls wearing panties out in public would have gotten raped. The violent crime rate was still rising toward its peak (1992), and young women had enough street smarts not to show off their figure in public in such an increasingly dangerous environment. Millennials could not be more naive, having grown up during the falling-crime period that we're in.
As it turns out, wearing skimpy and revealing clothing actually reflects lower libido levels. When real-life sex pervaded the atmosphere, women wore very baggy and boxy clothing to hide their figure from any unwanted attention -- and when libido levels were much higher, there was a lot more unwanted sexual attention out in public.
The contours of her torso were entirely obscured by a huge sweater, whose sleeves were also so baggy that you couldn't even see the outline of her shoulders or arms, and whose bottom fell low enough to also obscure her hips and buns (as they used to be called). Really the only outline she might have shown was her legs from a little over the knee on down. Pants were not skin-tight, but not baggy either.
The oversized sweaters, jackets, and coats of the '80s continued well into the mid-'90s (reaching its pinnacle in the sack-like overalls of the time), because women wanted to wait awhile after the crime rate had been falling to make sure it was safe to start wearing more figure-hugging clothing again, which began in the second half of the '90s.
This was no different from the baggy and boxy shape of the Jazz Age, another period when violent crime was on the rise, making young women street-smart enough not to invite unwanted attention while out in public.
Body-hugging shapes did not return until the Midcentury, when crime was falling and libido levels had mellowed out from their height during the Roaring Twenties. The iconic look for young women at the time was the "bullet bra" worn by the "sweater girl" -- someone naive enough to not think twice about parading her headlights out before the general public. Young women in the Jazz Age actually tried to de-emphasize their size -- don't want to risk getting raped, do you? But in the much safer 1950s, they didn't have to worry so much about that threat.
We can keep an eye on events like the No Pants Subway Ride to get a feel for whether the violent crime rate is edging upward or not. See also: jogging around a city, unaccompanied, in the evening, while wearing only a sports bra and booty shorts. Unfortunately it will be a lagging indicator, since exhibitionism will only decline just a little bit after the crime rate has begun to rise. By that time we will probably have official statistics showing a crime wave.
Nevertheless, women covering up will be independent confirmation that the threat of violence has begun to increase. Likewise, anyone who doubts that violent crime has really been declining just has to look at the behavior of those with the real targets on their backs -- and these days, early 20-something girls feel no danger parading themselves around without pants on the New York City subway. And in fact, they don't get molested or raped (ditto for slutwalks).
Believe what you want about official statistics -- the real-life behavior of those most directly and heavily affected is far more revealing (so to speak).