No OP - now you are backtracking - you aren't slagging off the dress, you aren't saying "look at the top and skirt being too big for her body" you are honing in on the one area that is her true size - her waist - it looks small compared to the enlarged top and skirt and creates an interesting shape, but it's the waist htat is genuine, and that's the bit you have an issue with - it's her thinness, not the dress that you are complaining about, it's her natural body shape you object to.
You would be quite rightly told to do one if say, you'd come on here when Lisa Riley was on Strictly and questioned if it was acceptable for a larger woman to be on TV wearing an outfit that showed off just how overweight she was and you were worried it was 'normalising fattness' and 'unhealthy role models' - you'd get 10 pages of people telling you that you can be larger and healthy, that 'real woman come in all shapes and sizes'
KK is a natural body shape, she's not like a lot of hollywood stars with breast implants giving an unrealistic ideal (it is a tiny minority of woman who can have large breasts and flat stomach with tiny hips - most people are fat all over or thin all over - but most female movie stars seem to magically have fat only in desirable places). She is not an example of an annorexic body shape. She's an example of a healthy, beautiful body.
I think it would do a lot more damage to only expose young woman to images of overweight woman and tell them that is a what 'normal' looks like. 'Normal' involves a vareity of shapes. Thin is just as valid.