Hard to prove-- I'm not nostalgic in general though. For example, I think food's generally gotten a lot better since the 90s.

A lecture about political rhetoric which shows that the nastiness level can change over time-- in particular, it goes into detail about shifts in which words got used in political discourse during the Nazi era.

I can tell you with certainty that Republicans and Democrats didn't used to have nasty names (Rethuglicans, Libtards) for each other.