Synth-wave and the relationship to science fiction aesthetics is something worth distinguishing from the nostalgia question.

A lot of synth-wave uses the vocabulary of science fiction — specifically the retrofuturism of 70s and 80s SF film and television. This is partly a nostalgia play, but I think it's doing something more interesting at its best: it's using the aesthetic of imagined futures to create a kind of temporal vertigo.

Retrofuturism is past and future simultaneously — it's how the past imagined a future that is now the past. Music that uses this aesthetic is occupying a position that is deliberately temporally unstable, and that instability can be a way of saying something about the present that direct commentary can't.

The synth-wave artists who use these aesthetics consciously — who understand the temporal complexity of the references they're deploying — produce music with a different quality from the ones who are just using the palette because it looks cool.