Maybe because these days it can almost be a crime to just be proud of just being a male/female. Being proud of who you are can almost always be offensive to someone else. For example some consider it offensive to be proud of your period/fertility because trans people can't have one/ won't be able to reproduce as the gender they identify themselves with. It can feel unfair to have symbols of femininity taken away because it could feel like you're not allowed to identify as feminine by having your period. The period in itself already is a point of discussion because there's still a lot of misunderstabdings about it and the feminine symbol could help people by identifying themselves as a "normal" (as in not weird or alien for having your period) healthy female. But I'm just speculating!