Northern Soul

I think the reason for this underground dance music was explained in the video when it showed The Osmonds.  If that is the music being played on the radio, it would drive people to an underground club scene to listen to good music.  I think it is also about rebelling against the "in" music at the time.  There will always be groups of people who don't fit in and want to be different.  The Northern Soul scene gave them the opportunity to be different and be around like-minded people.  If those people did not exist, we would still be suffering with the same old crappy music.