Well, we were a more culturally homogeneous people back then. Americans still created music and art for Americans. We were unapologetically western, and celebrated our place in the grand human pantheon through art in all its forms.
In my view, the corrosive and degrading influences of the left have slowly eroded the foundational underpinnings of our culture, and it's reflected in the gradual debasement of the arts.
The 70s were a time of incredible musical innovation and originality, pretty much everything done since the 70s has been derivative.