There's a fairly good analogy between SF and music. 70s music (and SF) was fat and bloated and slow. High concept stuff about galactic empires and gatefold sleeves and Serious Issues - Vietnam and the nature of reality.

And suddenly this fast, spiky thing appears, that's all nihilism and dystopia and edge and noir and anti-heroes and technology abuse, and instead of looking ahead a billion years it's looking ahead about 15 minutes, and instead of sounding like an orchestra it sounds like the wind over tensioned steel cables, and it wears sunglasses at night and it thinks technology is power and its just so gosh-darned cool...

Yeah, that's pretty much what it was like. Ok, it's all cliches now, but so's a modern punk band.