You know perfectly well that is not what is being implied, nor is it what people take issue with.
Why isn't a dinner gown acceptable?
Why specifically is showing off legs and sexualizing the woman a requirement?
What if they are trans f->m or non-binary and they would rather where a pant suit, or a tuxedo?
Gowns can be just as business professional, so can pant suits.
Longer if always ok