I think the nostalgia craze embodied in Vaporwave is the perfect storm of two things:
1. A lot of kids who grew up or came of age during the 80s/early 90s are entering into that age range of adulthood where feelings of nostalgia are starting to hit you like a mack truck.
2. I legitimately think that the 80s/early 90s is quite possibly the last great major significant cultural/aesthetic identity period in America.
I look at the decades like the 20s, 30s, 40s, 50s, 60s, 70s, 80s, and early 90s. Each of these periods have a very distinct aesthetic and cultural feel to them. Whether it be the jazz, big band, flappers and gangsters of the roaring 20s, the "Bugle Boy" singing wartime girls and traditional pop and appropriately worn fedoras and suits of the 40s, the bobby soxer greaser do-wop and rock and roll of the 50s, the hippies and psychedelia of the 60s, the disco, bell bottoms, and decadence of the 70s, and of the course the new wave, post-punk, synth-pop, big hair, MTV music videos and neon colors and over-the-top action flicks of the 80s and early 90s. Each of these decades/eras have a distinct identity.
Then sometime around the mid to late 90s, it feels like culture has either outright frozen, or has only changed in incremental unnoticeable ways since then. Overall the music, fashion and aesthetics of the 2000s and 2010s feel like nothing more than slightly altered iterations of what was going on in the late 90s. The closest thing I can think of as an aesthetic of the 2000s and 2010s is….maybe emo and scene kids? Which are nothing more than iterations on the Goth scene from the 80s. Other than that, people are still basically wearing T-shirts and jeans, or polo shirts or button downs. Maybe man-buns were a thing for a while? The point is, in terms of coming up with something aesthetically/culturally significant from the 2000s and 2010s, I'm really reaching hard here. Even most modern indie rock is essentially some variation of post-punk, synth-pop, or garage rock revival. In other words, regurgitations of essential 80s (or in garage rock's case, 60s) genres.
In short, I think the youth part of this nostalgia is that, like I said, the 80's/early 90s was the last period in America with a real cultural/aesthetic identity; today's youth are closes to that era, especially thanks to being able to easily access such music via Youtube and Spotify and the like, thus they are lacking on to it; sensing in it that missing something that is not present in modern culture.
So maybe you're right in that our current generation are picking up on something that is there that isn't in their current culture. I still think the so-called "critique of capitalism" aspect is bunch of hooey.