In certain songs, such as Happy, there are gaps between the beats and that makes us want to fill the gaps with our own movements or sounds. A few years ago, people wanted to figure out which songs make you dance. Usually the songs with too much complexity are not very good for dancing, but the ones with less of that tend to have simple beats that everyone can understand.
Which songs exactly? The 1950's hit "I've Got a Woman" by Ray Charles had a great beat and organization. The piano and vocals syncopated in a complex way so that you couldn't exactly sing along with Ray Charles, and you wanted to have apart in it in another way: by dancing.