Let me guess: the ones who “don’t see a problem” don’t have kids, right?
Yeah, there is a problem here. I don’t know why some adults insist on sexually objectifying young girls. It seems to be everywhere — in fashion, music, TV, movies, etc. The entertainment industry was never really about “morals” or treating people with dignity. Whatever their “art” demands is what happens, no matter the consequences.
Sorry the coaches at your daughter’s dance studio seem so unconcerned. As long as your daughter doesn’t have to perform any of these numbers, it might not matter overly much; but you know it’s only a matter of time before she will want to join them.