I have a trans woman friend who changed her name and is undergoing hormonal treatment (I must say, very successfully; she also did laser hair removal on the face with remarkably good results). She explained to me how important it is to "pass" as your chosen gender. So if a man wears dresses and makeup, the man would still not pass as a woman for a number of reasons including his deep voice. Hormone treatment increases the chances of passing as your chosen, self-identified gender.