Also, although the parts you selected are pretty reasonable and provide insight in this discussion, I would advise taking Fussell's book with some caution: it is an entertaining read but it is not definitive or really all that well-supported beyond his personal observations, and it slices a particular time and culture that seems to be on the wane (as the American middle class disappears, and the nature of the working class changes).
His "Class X" stuff was way off, of course, and is another thing the trappings of which became just another class marker (for hipsters, in fact, and some other fashion/lifestyle movements). Probably that's a recurring cycle with countercultures. Some specifics have shifted, though trends and anxieties have not so much, I think. A lot of the visible wealth now is (as usual) new money—often tech folks—so I think it remains to be seen whether their kids and grandkids will retain "lower" (largely upper-middle) class tastes and behaviors or integrate fully into the upper classes.
I could elaborate on some of the racial dimensions of the "hipster", though, if you'd like. It's not a topic I know much about, so yes, I'd definitely love to hear your thoughts on the matter.
The crux seems to be:
> [The] hipster—and the reference here is to Norman Mailer’s “The White Negro” essay for Dissent in 1957—was explicitly defined by the desire of a white avant-garde to disaffiliate itself from whiteness, with its stain of Eisenhower, the bomb, and the corporation, and achieve the “cool” knowledge and exoticized energy, lust, and violence of black Americans...
> The hipster, in both black and white incarnations, in his essence had been about superior knowledge—what Broyard called “a priorism.” He insisted that hipsterism was developed from a sense that minorities in America were subject to decisions made about their lives by conspiracies of power they could never possibly know. The hip reaction was to insist, purely symbolically, on forms of knowledge that they possessed before anyone else, indeed before the creation of positive knowledge—a priori. Broyard focused on the password language of hip slang.
> The return of the term after 1999 reframed the knowledge question. Hipster, in its revival, referred to an air of knowing about exclusive things before anyone else...
The rest of the article is sort-of a history of various trends in "hipsterism" over the period from 1999 to 2009. But this is quite a digression from the dominance of jeans...
Fussell notes this in his Class. The group he categorizes as "top out-of-sight" (mostly old money) is genuinely beyond caring about appearances and are where you get a lot of "eccentric" rich-person behavior like wearing really cheap clothes. Upper-class folks, especially younger ones, may very carefully and deliberately dress way down, especially when traveling (for some reason), though they will not, and will not intend to, actually blend in.
Separately but somewhat relatedly, he claims that higher classes will tend to buy unexceptional things where spending more is seen as primarily a status signaling thing, and especially when the thing is in any way technological—so buying a flashy, expensive, new car belongs to the sensibilities of the upper-middle classes and lower (regardless of their income—talking about socialized class, not income) while the comfortably rich might just own a beat-up Chevy, or an old luxury car.
Where you do not see people do it is when there's a risk they might actually be mistaken for belonging to any part of Fussell's "prole" category—so, upper-middle and, especially, middle.