What I'm saying specifically is I think it's better to get to know people before having sex with them, even if it is casual sex. I don't define casual sex as a one night stand. So I'm not saying you have to be in a relationship with everyone you have sex with, but if you aren't considerate of them and don't care about them in a general sense you're a jerk. In my moral code, it's not ok to dehumanize the person you're having sex with. There are many reasons you might have sex with someone but not want to be in a relationship with them, and most of them boil down to selfishness, but I think you can be selfish to the mutual benefit of both parties and still not be a jerk.
And sure, one night stands happen, often when there is alcohol involved, and it's not wrong to have one, but it does run into problems when there is a question of consent.
And the whole number rating system just grinds my gears, I can't say why. I just think people are attractive, or I don't. I also don't like when people talk about "leagues." If I had to hazard a guess, I'd say it's because it places a value on someone based purely on their sexual attractiveness and it turns them into a commodity. And let's face it, women are subjected to this far more often than men are.
Superficiality is an inborn part of human nature, but I think it should be balanced by respect for others and an attempt to understand them. And of course superficiality is degrading, girls are told every day that their value lies purely in their looks and their primary goal should be to attract boys. They are told this by the media and society at large. I'm definitely not saying boys don't suffer from that as well, but the brunt of it is borne by girls.