Crack-ing Up

Please, please, somebody with an insight into the world of fashion, help me out here: Why would anyone ever introduce the concept of "low-rider" jeans? Was the world facing a desperate ass-crack shortage that could only be resolved by crack-revealing pants? Who is the ad wizard who came up with that one??? Was Calvin Klein lounging around his penthouse one day, dreaming up the next great fad in the world of denim fashion, only to glance over and see his refrigerator repairman bent over, revealing several centimeters of butt-cleavage?