Thus, I think the classes you propose would have worked if they dealt with "how to not treat girls like crap" and still get regular sex from hot women.

Honestly... you have to change the whole culture.

The part of American culture we're fighting with is a culture of treating people like crap. In business, it's the idea that employees and relationships are commodities to be traded and exploited, and the vicious and nonsensical competitions over nothing (similar to Game culture) that nonetheless determine who ends up in charge and who gets fired. How could one expect people to be decent around sexuality when they aren't decent at all with regard to the other things they want (e.g. money, jobs, social status)?

We have a culture that glorifies people who break rules and trample others to get what they want. How is that not going to cause this sort of behavior?

American college-style hookup culture is so focused on acquisition, manipulation, the bad kinds of competition, and emotional immaturity that it can't be separated from horrible behavior.

I'm not religious. I'm not going to claim that there's some supernatural being that cares about human sexual behavior in such prurient detail as the traditional Christian God, because there (almost certainly) isn't one. I also don't think promiscuity, polyamory, and extra-relational sex are unhealthy for everyone; but they seem to be unhealthy for most people. Building a culture that glamorizes a sexuality that only makes sense for about 25% of people (wild guesses: 15% of women and 35% of men) is a recipe for disaster.

Where religion gets sexuality disgustingly wrong is when it comes to the letter, rather than spirit, of the law... and also puts sex under different, extreme, and often misogynistic rules as opposed to the rest of human behavior. Traditional morality is actually right on the basic idea (sex, for most people, should occur only in long-term loving relationships) but, unfortunately, tied up with bigotry (religious, racial, gender) and there are some really awful (and usually hypocritical) people who take sex policing (which has no place in modern society) to heart and go to the extreme with it.

To make it clear, I don't care what other (consenting, adult) people do as long as it doesn't affect me, and in general it really doesn't. However, the culture is sick and "hookup culture" is a symptom, if not a cause. It no longer affects me (30 years old, happily married) but if I have kids, I really hope they can come into a world where respect between the genders is so normal that these behaviors don't happen. But, I don't see that problem as separate from the more basic fact that most people don't respect each other in this society.