What you’re hinting at is one of the reasons why most Orthodox women don’t wear pants: kli gever – the prohibition for a woman to dress like a man. (Beged isha is the corresponding prohibition on men dressing like women.) It used to be that pants were only worn by men, in the same way that skirts are only worn by women now, so wearing pants was the equivalent of wearing men’s clothing. But you’re right that there are certainly pants out there today that are specifically made for women, so kli gever can’t be the only reason behind skirting pants.