The essence of each Mitzvah is transmitted, applied and explained to us by the Gedolei HaPoskim of each generation.
Just as they tell us the nature and practice of laying Tefilin, they explain to us what the appropriate guidelines for Tznius are for both men and women. We may not be sensitive to the subtly of their opinion, but must recall that Da’as Torah is developed from ten of thousands, and for an older Posek – hundreds of thousands, of hours toiling in Hashem’s Words. Our sentiment, however, is a product of our imperfect environment, media, social milieu and advertising.
In Orthodox Judaism policy decisions about Halachic practice, be it in Hilchos Pesach, Berachos, Shabbos or Tznius are the realm of the Gedolei HaPoskim and Da’as Torah.