Possibly this. Ladies got in cheaper, of course, because the dancehalls wanted more of them. Ballroom culture has been extinguished for the most part - yes, you'll always find people who know how to do it, and where to go. But the dance halls are gone, replaced by clubs where people pogo in solipstic frenzy. The idea of gliding a partner around on the floor, or even making halting steps while you held your arms at an unnatural angle while your partner endured it for the sake of dime - gone.

Wonder what the old-time dances were. The Charleston?