Not arrogance -- ignorance. And if someone explains that they're doing something to help those poor, stupid folks from a hundred years ago who don't understand what contraceptives are -- then I have a right to be angry -- I'm who they are talking about.
It's an unfortunate truth, as well, that women have always suffered from a lack of sexual education about their own bodies, their own rights and their own freedom to express their sexuality as they so choose. Acting as though people from the past are the only ones who don't know what they're doing is ignoring the problems of the present -- and problems I still see very prevalent in conversations here.