YMB - I am not sure that you grasp why there is the upset about dress codes.
The places where you have worked may have asked you to wear a tie, but they didn't ask you to wear tight trousers and a tight shirt, or to dye your hair a certain colour, or wear make-up did they?
The point they are arguing about with certain dress codes for women is that it is not about appearing to be smart and professional - which is the thinking behind a tie for men - it is about making women look more sexually attractive, and obviously that is not acceptable.
If a woman wishes to wear a short skirt or a loose blouse or shorts, as some of your colleagues apparently do, then that is a matter of personal choice.
Making a woman conform to an image that is based purely on her sex appeal is not - and that is what the protest is about.