Catholics make enormous sacrifices to live their lives morally, to support their parishes, to help others within their communities and to provide their children with religious instruction and moral foundations. To expect them to not enjoy sex in their relationships is just stupid.
I will add that these Catholic women who use birth control still overwhelmingly support the right of the Church not to have to pay for it if they object.
Artificial contraception is sinful because it breaks the connection between sex on the one hand and marriage and openness to new life on the other. That has always been the Catholic teaching and, until the Anglicans broke ranks in the 1930s, that of other Christian denominations as well. Morality is not enacted by democratic vote. We have seen the utter moral sewer that our society has become since the separation of sex from marriage and from openness to life that occurred with the pill. Pope Paul VI was prophetic with Humanae Vitae, regardless of how widespread the dissent is. We are in an era where moral heresy is rampant, and so much of it centers on making sexual gratification the highest human good.