I have a mixed responce to the op, I think you are talking a little bit of tosh, a waste of money, hmmm, well you need a pair of ballet slippers a leotard tights, and a hairband and grips, (hair in a bun) as you progress you need points, and for different levels you need a skirt, but thats it so a waste of money, no.
But as for body image, I danced for 13 years, I was clasically trained, it was hard going strict back breaking, it took absolute commitment, and failure was not an option, and yes body image was part of that. My teacher was a high achiever who had never quite made it, she would tell us that she had lived of bread and water, and tbh thinking back, it was not weird to hear that, so it must have been spoken about openly in class. But my point is when I was 12/13 I was told that if I wanted to seriously think about this as a career, or if I really wanted to achieve anything I would have to be a different shape???
I have always been of the opinion that if I had a dd, which I now do, she is 3 and loves to dance, she is a natural, that she will not do ballet, no way no how.
Some children do dance classes, some children do ballet, but im my humble opinion, a child should do dance classes not ballet, and if it is a ballet class I suggest that you listen and watch, not just your dd class but the older childrens classes, and do it carefully, because their is a lot of underlying parts to ballet that are truly for want of a better absurd. I have been smacked on the back of the legs with a cane for not lifting my leg haigh enough, I have been mocked and ignored I have been ridiculed for not being good enough, when in actuall fact I was far past bloody brilliant.
Oh and there will always be one prima in the group, the rest of the children will be mocked for never being her, that is ballet, it is one constant competition.
And I love to dance, it gave me poise, brilliant balance and a confidence that others lack, but I hated ballet, and will not subject my dd to it.