Cultural Differences in Cognition
If people from another country behave differently, such as how the Japanese are obsessed with politeness and etiquette, then those people must also think differently. Modest behavior must be linked with modest thoughts, and vice-versa. While polite people could have impolite thoughts, the contrast would create cognitive dissonance, and there's only so much our brains can handle.
The pattern where cultural nostalgia is always 20 years ago may have more to do with the natural progression for people’s tastes
As teenagers, our tastes are aimless and focused on the present. In college, we move beyond the mainstream towards novel or obscure interests. After we exhaust those in our college and early-post-college years we look towards the youth before our youth. We seek new depth through the back catalog.