The Church wasn't designed to be mainstream. It is counter-cultural -- it doesn't change its teachings (which come from God to begin with) just because something becomes popular.
I know that by now the Catholic Church could be considered "counter culture." I am not agreeing with drawing up pre-nups., in fact I would not sign one. Besides being against church culture, I guess one could say that I agree fully with the position of the church: that a pre-nup. starts marriage out on the wrong foot.