Sorry, but I totally disagree.
Remember the five key elements? Fitness magic is one of them. A little performance is part of our jobs. We signed up for this approach. If we don't like it, there are other programs that are more serious, or you can make your own free style classes as serious as you want. And - I might add - no one says you have to dress up, etc, in your own classes. But then find the fitness magic elsewhere ...
I love themes and seeing what outfits they are wearing, and what funny cues and performance opps they come up with, then taking them and making them my own, and adding to them.
So I have to ask - what is wrong with teaching Combat in a dress, Step in boots, or Flow without a shirt (hey now, I didn't know about that - better ask a Flow instructor friend if I can borrow her DVD
) So long as movement isn't comprimised (and nothing I've seen has been) who cares? It's not like she was wearing a mini skirt and couldn't kick. Everything they wear that I've seen has been cool and different, but functional. Those boots are specific dance boots - they are made to be worn like that!
I don't teach Vive so I can't comment on that, however I don't see teaching being compromised myself. And if you can add some flair while doing your job - freakin' awesome!
To each their own, and if its not for you then that's your call, but wanted to add my $0.02.
Free the body.
The mind will follow.