It's an interesting topic. My wife and I have a rule that, if a music video is on the TV, we have to turn it over if anyone, male or female, is dancing in their pants. We rarely see a video all the way through.
It is something I have noticed in Jazz as well. The sexualisation of ANY female musician, not just singers, is, to my mind, an unfortunate trend. Eg. Diana Krall cd covers. If you see them in order, she is wearing less and less each time. It's so unnecessary. These are talented women who shouldn't have to be presented in this way. As s promoter, I have nevertheless observed that Jazz audiences like a 'pretty girl' as much as any audience. The tend to behave, though, and keep their thoughts to themselves.