The mid-late 70s sucked; disco and generic pop like Journey, for example, provided the soundtrack of the Liberal Golden Age (August '74 to November '79.) The only real good stuff came out of the emergence of punk/new wave. And I have my doubts that rock music actually made it into the 21st century.
Rock and rock and roll both made it into the 21st century but the dominant youth culture never sees or hears it.
Then again to hear Bill Clinton tell it in 1992, there was no grunge or electronic or garage... he said that growing up in "this" era he would only have the "choice" of listening to heavy metal or rap so he would probably grow up listening to rap. He was trying to be PC and to show he was hip but it showed just out of touch he was with Generation X.