As far as ballet dancers go, there is a bit of a trend for vests+pants as costumes in modern works (attached pictures = Olivia Cowley & Edward Watson in Wayne McGregor's Carbon Life & Sarah Lamb & Federico Bonelli in the same choreographer's Infra)... in terms of them not getting sweaty, however... just being under stage lights is enough to make most people pretty warm, even if you're, say, hunting party in Swan Lake. All of ballet is hugely controlled & precise, of course, but as for slow... There are things where just the counts would be enough to make most people break a sweat (looking at you, Rite of Spring, but I think it's Les Noces that's got some totally impossible bits); & some things the corps de ballet dance are so brutal they're known to make people vomit on the regular (snowflakes... actual buckets in the wings during Nutcracker season... nice...). Lots of cynets in Swan Lake is speedy (as well as requiring precision & being perfectly in synch with 3 other dancers) & of course if you're going to whip out sorry not sorry 32 fouettés in the black swan coda you need to be going some. Kitri in Don Quixote, Canary Fairy in Sleeping Beauty, Spring Fairy in Cinderella, 1st Odalisque in Le Corsaire, & Zhanna in Flames of Paris - all examples of ballet variations that are anything but slow, however much precision & control they demand. The costuming varies, sometimes it's closer to a classical tutu, but usually it is a dress (as you might see in Giselle or Fille, for example) & tights for Zhanna - am resisting temptation to put in links for other variations, but the artistry here is just too beautiful not to.
Er yes. Slightly confusingly, my point, there, pretty much:
- Ballet dancers do sometimes essentially perform in their scanties (& of course have been pushing boundaries on this for over a century; Nijinsky's costume for Faune was Pretty Scandalous [though obviously it was basically humping the set that really set people off... & yet it was Rite of Spring that caused the riots - the music for it at that: people are weird ]).
- It is ridiculous to assert ballet dancers will neither be dancing quickly nor getting hot&sweaty.
- It is perfectly possible to perform incredibly complex, precise & physically demanding moves with decidedly more cover than the people being discussed in the OP: in Le Jeune Homme et La Morte the male protagonist wears dungarees; & in The Judas Tree the men wear jeans. One (female) former Royal Ballet dancer I used to do class with wore jeans to class pretty regularly - if you get the right ones you can still do the splits/hit a six o'clock penchée/get your grand battement à la seconde up to your ear (etc etc). Costumes can be designed to look like street clothes but enable extra movement.
As to whether YABU... On balance, I don't think you are.
Yes, women should be free to dress as they wish, purely to please themselves, & without being judged by others. However, what should be & reality are all too frequently some distance apart; & when it comes to women's clothing (displayed, of course, on women's bodies) things are nowhere near as simple as they should be. Clearly one can choose to ignore all the messy socio-cultural stuff, but that doesn't stop it existing & being problematic.
There are massive ongoing issues around sex & consent & "well if you were dressed like that you were asking for it...". There is stuff around the expectation that women should make themselves available to men to be gawped at - & that they've a right to do so (& to take pictures/make lewd comments/provide other hugely unwanted attention) if you "show too much flesh" because you must be seeking attention rather than, say, wearing a vest-top & shorts in 28C heat. Women also police each other hugely aggressively; & certain sections of the media are only too happy to help.
What matters most here, I think, is that the performers concerned are role models to lots of girls & young women. The celebrities themselves may face negative press, but there is potential for their young fans to face more immediate consequences if they try to emulate them. Obviously "you must be ashamed of your body & never show it" is not a good or healthy message to send girls & young women; but I don't think "you have to [be willing to] strut about wearing very little if you want to succeed" is, either.
Of course nobody should feel entitled to any kind of control over another person's body or choices, be that having some weird "right" to ogle; or the notion that we should be keeping each other in line in an almost cult-like fashion with our policing of behaviour. Those things need challenging until they change. While they still exist, though, arguably performing artists have a responsibility towards their fan base - especially people like Taylor Swift & Little Mix, whose following will include HUGE numbers of [pre-]pubescent girls. They can't afford to be caught doing drugs or getting blackout drunk or having a sweary slanging match over a parking space - yet their clothing doesn't reflect a similar set of values/brand. Presumably it's about broadening their appeal - only a limited number of households will actually ban them outright for the costumes/dances; & they'll be outnumbered by the interest they gain from people who LIKE the costumes/dances.
Ach. I've not slept at all & am in too much pain to properly articulate what I mean. But it's taken so long to write I'm going to post it anyway & face potential I'll get internet-yelled-at by posters thinking I'm blaming Taylor Swift for children being sexually assaulted, because I've not managed to be coherent-cogent. It's just such a big tangly thing: yes, lovely, wear what you like; um, role models & responsibility; ugh, people basically suck; we should challenge the crapness of people/awfulness of people will never change if accept status quo or simply aren't super-aggressive in tackling it/nobody is responsible for people being crap bar individual who is being crap/but you can't view anything in isolation; once again, humans are awful. (But ballet. Ignoring the Awful Humans over there, obviously.)
As I said, no sleep, much pain, total thoughtjumble.