I'm worth cornutt. It's popular because it fiills in a rhythm hole. The slow,romantic songs that don't fit for rumba or bolero (Bolero in a nightclub? As if!

) often fit NC2S. Besides, you can learn the basic in a group lesson or two and be good to go. Besides, it's worlds better than the old clutch and sway, which is much many non-dancers would normally do to NC2S songs. And it's romantic without being suggestive or nasty, the way clutch and sway can be. Perfect for exactly what it says -- dancing at a nightclub. Although I have to say I've seen a fair bit of it at weddings, too
