Over at Steve Sailer's, they're discussing if and why style has stagnated since the 1990s. The idea is that every 20 year period before 1990-2010 (e.g., 1970-1990, 1950-1970...) showed a lot of change, while the styles of 1990 are recognizable and "in style" in 2010. The thesis is a bit overstated, but basically I agree that new ideas in the realm of design have slowed.
Here are some reasons I came up with that might be contributing:
(1) A lot of creative and consumer energy has gone into electronics in the last twenty years. Who's going to concern themselves with the latest sneaker or trouser cuff variation when the latest version of Doom-Halo-Call of Duty is coming out? You're just going to play it in your sweatpants.
(2) Body style has stabilized. There were massive changes in standards of beauty for the raw human body for both sexes from the 1900s to the 1990s. Since the 1990s, the standard has stabilized because the science of fitness has stabilized and, with it, the ideal image of a fit person. (Just think, the 1970s were the age of skinny runners, then the bodybuilding revolution of the 1980s. Then the huge buffness went out in the late 90s. Now we have CrossFit, which pretty much represents a stable not-so-big buffness continuing into the 2010s.)
(3) Black culture isn't feeding into and changing white culture anymore. Mostly, they're just one big mishmash now, and to the extent they're not, they won't be. Baggy jeans are everywhere, but the four-button technicolor suits with matching hats and walking sticks are never going to be hip with white folks.
(4) Much more pre-fab building products, and Lowe's or Home Depot everywhere. Ceilings in institutional buildings look the same from coast to coast.
(5) Death of Art. A lot of changes in clothes and architecture were driven by the belief in Art, which is dead since the 1980s, or at least the early 90s. Remember Robert Mapplethorpe? He was the last artist who could scandalize anybody 'cause nobody cares anymore. Yeah, Frank Gehry's in demand for big projects, but nobody's going to design a post office, let alone a split-level ranch house, with "Bilbao influence."
(6) Death of Romance. Neuroscientists and ethologists like Jaak Panksepp have a lot of trouble figuring out what love is. I think the reason is that love is somehow a construct that arises out of society's interference with the sexual dynamics of the state of nature. Romance is the instantiation of love in art and culture, and its churning unnatural roots that can't settle on simple concepts like physical lust cause romance to be intellectually productive. Since the 1990s, we have moved substantially away from love toward state of nature sexual relations, and romance has died as a result.
(7) Death of the Heirloom. (More generally, death of the past.) My parents' house is filled with things they inherited from family, bought at estate auctions, and were given for gifts. I know not one younger person today who has a piece of heirloom furniture. Nobody cares about these things with the result that many people don't consider much beyond lowest common denominator concerns in decorating.
(8) Perception of change is confused by the proliferating number and combinations of styles. I still have clothes from the 1990s that I can wear today and look normal. But in the 1990s almost all my peers were wearing the same thing, and subcultures like "skateboarder" were small and highly differentiated. Today, the attributes of 1990s "skateboarder" are mixed in with all sorts of other styles. There's much more acceptance of vastly different looks. When I go to the opera in Montreal, I see everything from black tie to jeans and t-shirts, from dolled up ladies to goths. And the division isn't the cost of seats.
On the up side, reason #8 has allowed the developement of vintage girls, young fogeys, and chaps.