Other explanations could just come down to the structure of our current society.

I can see a clear and quantifiable decrease in my family support structure between childhood and now. Of course that's mostly due death and moving away from home. But my answer would be entirely different if I lived in a multi-generational home or kinship group. Which was the default for about 99.9% of human existence.

Music, fashion, and tastes are a lot more subjective though.

I always go back to that line from Men in Black about the difference between a person and people.

In aggregate we really are the worst.

People often forget that nostalgia is the secret spice that makes the past great.... not the actual past.

And nostalgia is nothing more than there's shit happening in our brains at 10ish-20ish that doesn't happen any other time. Hormones and energy and lack of responsibilty and first experience bias combine to create a dopamine cocktail we cannot recreate.

I mean, I'll die on the hill of 90s was the best music, TV, movies, video games, and fashion. But I know that it's not objectively true. But that's how it feels for sure.