Most contemporary music is trivial and the styles come and go at the whim of the record companies, and according to the changing fads of an infantile audience. You might dance to it today, and be laughed at tomorrow.
REAL music lasts. And the dance styles that have been developed (and there IS development, nothing is unchanging) have endured and will continue to do so, probably all your dancing life, because the steps and figures can yield such pleasure and interest at so many levels.
If a song was good thirty years agpo, it still is now. New versions will be brought out regularly, but the originals will still be danced to. How much of the drivel that your friends have on their IPods won't have been wiped and replaced with some new dross by the middle of next week?