If everyone has a choice of skirts dress shirts and trousers then that should he sufficient surely .
But giving boys/men the option of wearing dresses or skirts is a non choice isn't it? At least currently. There would be uproar if it happened.
If you can't drive and I give you the options of driving around in a car or a van that isn't a choice is it?
Or you can't swim but I give you the options of swimming or diving for pe then it isn't a choice is it?
Trousers are considered unisex. They are mainstream for males and females to wear. Whether you wear them or not they are viable options and it is your choice to wear them. So giving girls the choice of wearing skirts or trousers isn't giving them a masculine and feminine option. Both are considered equally valid options for females.
Skirts and dresses are not considered valid options for males at the moment. So how is giving those as an option a valid choice? It isn't.
Women suffer many instances of inequality and they are wrong and need to be addressed and corrected but when it comes to clothing I do think men and boys are treated unequally. What is wrong in seeking to address that inequality? In this instance what people are arguing for is to treat females better than men. I fail to see how you can do that with s straight face when you argue for equality for women.