Do you feel you connect with people or better understand them through physical affection or sex? Do you think many other people feel the same way?
I think it would be hard to argue otherwise. I'm not saying that sex is /more/ important to understanding somebody than conversation, trust, et cetera... but it's a fairly simple fact in my mind that if you have sex with somebody, you /will/ learn more about them. Even if it's just, say, whether or not they snore.