Cyberpunk is an explicitly dystopian genre setting so I'm not sure "nostalgic longing" is how I would characterize it so much as searching for a kind of catharsis or fictionalized escape from the things about it people feel parallel their own lives.
Neither would I. If Neuromancer wrote about 80's Japan corporate culture it is because it was written in the 80's and tried to extrapolate that to the 21st Century.
