It's funny that rock and roll started out as dance music, but by the time radio consultants sliced and diced its definition in the seventies, it became the antithesis of dance music. Rock and roll would have never come into being if it weren't for the dance floor. It was cultural celebration music, which is what dance music has always been. Early rock and roll was essentially fast swing music, borrowing from aspects of rhythm & blues on one hand and country on the other. Even in the sixties when rock went psychedelic, it was still dance music at parties. Although it had been the advent of folk/rock that redefined rock as a more mature listening experience, even folk hits like "Me And Bobby McGee" recorded by Janis Joplin still found their way on the dance floor. Rock was party crowd music and it powerfully brought people together.
The underlying spirit of rock from the beginning was a sense of liberation from the old rules. Even rock started out as swing dance music that involved traditional structure and dance steps. But by the sixties part of the rock ethic was to tear down traditional structure. Rock then became not only a celebration of freedom, but a style that had no rules. That's why we see from the footage of Woodstock in 1969 so many people dancing mindlessly without regard to dance steps.
But disco music brought back traditional dance steps and a more uniform structure to pop music, which made disco look like the enemy of the rock ethic. While rock had evolved into serious message-oriented music that dwelled on frustrations in relationships and society, disco was more about leaving seriousness behind. Rock had been the celebration of individuals uniting over big picture ideas, but disco was simply about the limits of the dance floor and gyrating body parts to stimulate sexual fantasies and behavior.
The most interesting paradox about disco was that while its lure was rooted in mirrors and narcissistic expression, it was certainly not about being an individual. It was about conforming to materialistic fashion and traditional dance steps. Disco turned out to be the band aid that pasted the establishment and the counter-culture back together, marrying the dance steps and materialism of the establishment with the party sensations and sexual revolution of the counter-culture. In the process, liberal rock artists were angered by the disco invasion, and tried to tear disco down for being repetitious dance music. They saw it taking over so they began lashing out.
Eventually the music industry decided that disco was dance music and rock was not dance music. While this was going on rocker Bob Seger had a huge dance/rock hit in 1979 called "Old Time Rock And Roll" which paid tribute to the original spirit of rock and roll dance music and criticized disco. Another anti-disco song was "Do You Think I'm Disco" by Steve Dahl, which was a parody of the Rod Stewart hit. Other songs that took jabs at disco included "Heat Of The Moment" by Asia, "Rock This Town" by Stray Cats and "Sausalito Summernight" by Deisel.
But despite this false optimism that disco was dead and that real music was back, the off-shoot of disco ended up ruling the decade on the charts. This off-shoot was never called disco, because disco simply became a negative word in the eighties, due to backlash from over-exposure. The new pop came to be known simply as "dance music" or "crossover music," which fused pop and soul.
It was music that had nothing to do with rock and roll rebellion or shaking up the status quo so that it would blend in and not stand out as background music or innocent dance music. It would be slower tempo but the idea of repetitious drum patterns with heavily pronounced beats, shallow lyrics and slick production would inevitably be the sound that reeled in the mainstream. One of the first records to adopt this highly refined industry sound as far as production technique was "Bette Davis Eyes" by Kim Carnes in 1981, although the lyrics and melody were somewhat creative, despite being a throwback tribute to a pre-rock legend.