Actually, emotional vulnerability (susceptibility to being attacked or injured) is at the essence of humiliation. One reason we're vulnerable during sex (assuming it's with a beloved partner) is that we recognize the depth of our hypocrisy in that state, because of the obvious contrast between the treasured intimacy exhibited during the sex act, and our public, more civilized and sophisticated life which we also prize.

The private and public sides of this civilized life are obviously in conflict. Sex is humiliating because it forces us to acknowledge how what we truly want is for the most part grossly underserved by what we end up doing most of the time in public, including what we do for a living, how we participate in capitalism and consumerism and tribal politics and hypocritical religions, how we treat strangers and the planet and so on. This is the hypocrisy I'm talking about, which hypocrisy becomes obvious while we're engrossed in the sex act.

I address your other criticisms in more detail in several earlier articles. If you're interested enough to have read the above article, you might be interested in the two linked below.

I realize the topic seems offensive, but the problem of this hypocrisy or absurdity is so glaring to me that I'm frankly offended when people take offense by this criticism of human sexuality. I'm just a messenger.

http://rantswithintheundeadgod.blogspot.com/2016/05/sex-and-authenticity.html

http://rantswithintheundeadgod.blogspot.com/2015/04/clash-of-worldviews-sex-and-love-edition.html