Heh. This writer's American, huh?
I don't think it's meant to be sarcastic; I think it's directed more at the fact that dance doesn't get mainstream radio play. You've got your rock stations, your country stations, your rap stations, but no dance stations. That and the fan base, while large numerically, isn't necessarily demographically wide.
I just think that the majority (really ALL) of mainstream "pop" music - the stuff that gets played on your local AusStereo station or on Video Hits - is dance music based, not rock based as it was say 10 years ago. The style of music is dance, the theme of the videoclips and fashion is dance club based. Sure, J-Lo does about as much for electronic music as Creed do for rock, but the fact is the teenyboppers listen to it and identify it as "dance" or "club" music.
I'd classify Jennifer Lopez, Britney Spears and most boy bands and such as variants of "R&B", a debased, MTV-ised McHipHop (of no relation to rhythm and blues).
Is this piece meant to be sarcastic, or nieve? Dance music is THE mainstream. At least where I'm from. Dance fans outnumber "hip-hop" fans 3:1 and "rock" fans 10:1.