Lots of things are lo yilbash. Dieing hair carrying a weapon and so on. Anything that a woman normally does is assur for a man and vice versa. Thats why women dont go to war.
And his wife is a moredes because we assume that both of them want to follow halacha even if they act differently – see the meforshim about beating a man to give his wife a get. If she doesnt want to follow halacha then shes a moredes no different as if she didnt cook kosher meals or go to the mikvah.