In the dopey hippie-mentors-square-padawan film Flashback, Dennis Hopper, riding easily on his 60s street cred, optimistically observed that “The 90s are going to make the 60s look like the 50s.” Uh, yeah. Somehow, Hopper’s character missed the fact that another era already looked like the 50s — the 80s — thanks to an over-investment in…