This is the reason why STEP you was the most successful song of 2005 byayu. Catchy lyrics, easy to follow etc. It's not that groovy as london bridge etc though. Personally I'd rather dance to something like STEP you than RnB orhip hop beats though.
THere's one more thing that I don't htink anyone mentioned. When you're on the dance floor you also sometimes try to "live into" the music, kind of act, and a lot of what's going on in clubs is checking other people out, perhapsto bring them home. If the lyrics diden't reflect this in a way that people can relate to, then how could people act into it.
If this came across as a bit uncomprehenable, I*ll try to give an example: I was dancing in a club with some friends to hip hop music. the music was great, but all of the sudden a song in which a girl "commanded" a boy to do some... vacum cleaning of her carpets...
(A bit more directly though, it was really naughty.. ) We had to leave the dancefloor. My girlfriend (and me too) just woulden't feel comfortable looking someone into the eye, grooving, perhaps even miming the song when such a thing played.
A song like "TOXIC" by Britney on the other hand makes everyone run to the dancefloor and totally act into it because there's just about enough innuendo to stand. Allthough the meaning is somewhat the same.