Casti Connubii also said all artificial contraception was intrinsically evil (54). The portion you cite needs to be read in context of the whole, the just laws are those set to help people protect their chastity (Casti Connubii 123) The pill does not aid in that effort, but rather frustrates it. In a truly loving an mutual giving relationship nobody is thinking about money, but the greatest good for the other. NOT pumping my wife full of synthetic hormones, I believe that to be a great good.

I'm failry certain you can find a way to disagree with that point, but I think it is a matter of historical fact that the pill has lead many to believe chastity to be some mythical value.