Please take a moment to reflect how much damage this type of thinking has done in the world.
This book isn't just useless and misguided, it's positively evil.
> It follows that many of those who died from AIDS would still be alive today had the Catholic Church abandoned its condom ban in the 1980s, as it became clear that condoms were (and still are) the most effective practical measure to prevent the spread of the disease.
http://en.wikipedia.org/wiki/Catholic_Church_and_HIV/AIDS
Also forbidding sane family planning and the prevention of unwanted offspring, where lack of necessary resources causes even more disease and more death.
Having been an Evangelical Christian and 'assistant teen pastor' in a previous life, I've seen this in action in many different areas of life. People constantly did things they believed were wrong, and the combination of not being prepared or informed about those things and feeling ashamed about it afterwards led to a lot of suffering.
BTW, I'm not saying I agree with the content of those lectures. Only that dismissing them because you think the modern world doesn't hold those views is silly. And, yes, I'm aware that more recent pontiffs have expressed different views.
The teachings are most definitely relevant, if for no other reason than that perhaps a billion people worldwide consider the teacher to be directly important to them.
Readers here may be interested in studying a somewhat different take on human sexuality, John Paul II's Theology of the Body[1], which "presents an interpretation of the fundamental significance of the body, and in particular of sexual differentiation and complementarity, one which aims to challenge common contemporary philosophical views."[2]
[1] http://www.ewtn.com/library/PAPALDOC/JP2TBIND.HTM
[2] http://en.wikipedia.org/wiki/Theology_of_the_Body