It's a pretty important social custom in a lot of cultures. I feel for you as there are times when I really, really don't feel like dancing but also don't want to be the odd one out.
It doesn’t really seem like an important one in US culture anymore, thankfully, so much as one of the few remaining fronts on which it is oddly socially acceptable to pester people.
I dunno, maybe it's not as important as it used to be, but high school dances have some cultural heft, and dancing is a centerpiece of the American wedding tradition. Weddings are pretty universally important across cultures. Plus America is becoming more Latino which I understand values dancing pretty highly.
