AN -- I get your point (many social taboos, and religious restrictions, have roots in sensible practices). Traidtional Jewish customs and observances have many roots in middle-eastern hygeine requirements. And I'm sure the Hindu concept of the sacred cow must have something to do with historical practices concerning meat or irrigation or something.
But I'd have to disagree with many of your specifics. For example, few societies, whether modern or tribal, follow strict monogamy, but instead practice one thing and preach another (just like we do in North America today). Most monogamy arises out of resource restriction. Just about any human (male or female) in history who has had unbridled access to extra material resources has used them in some way to foster sexual experimentation with a variety of partners. The "rules" were broken, because they could be.
Another example, AIDS can and does exist outside the homosexual community, and much research points to it first developing among monkey breeders and zookeepers in Africa, for example. But, that having been said, the rapid spread of it across North America in the early 1980s was certainly due to a type of "culture" that forsook the benefits of traditional religious teaching, in which fluid exchange with multiple sexual partners was a too-regular practice. It now spreads most rapidly to female recipients of vaginal-penile coitus intercourse, a decidedly non-homosexual act. Oh, and intravenous drug users, who could be of any sexual predilection, so it's not even a "sexually transmitted disease" for them!
The point here that I'd make, is that there isn't simply a "strict" life that can be free from threat, and the opposite, a "self-indulged" life that engenders greater threat. Religions, and a simplistic view of human history, would point to the act of taking excessive liberties, as somehow damaging to humans. But a similar investigation can make it clear, that taking too few liberties might be equally damaging. Inbreeding because your tribe won't have sex with the female from the neighborin clan, would doom your entire tribe to eventual death. Insisting on staying with a given partner could lead to death from a localized disease; again, your genes die out. Many instances where self-restriction is a biological or cultural ill can easily be thought up, and they're just as common and likely as those in which self-indulgence is the dangerous path.
My hope would be, that humans eventually "get" the idea that we're primates just muddling through. As a few others have pointed out, the idea of an "ideal" man or an "ideal" way to run a society tend to have the disadvantages of thinking that people are perfectible. In addition, the notion that someone who is not (currently) "socially strong" needing help, often fails to occur to the perfectionists. We have strength, partly, in requiring many of us to compete in a harsh way that weeds out weakness, as the objectivists would imply. But we also have strength in sympathizing with the losers in that fight, and helping them limp along behind, because you never know when their particular gifts might come in handy. Mongrel vigor ... So I can't subscribe to any one "theory."
An interesting aside to this whole discussion, is the concept of self-perpetuation, as expressed by John Ralston Saul in his fabulous works of modern social philosophy. The best of them, I think, is "Voltaire's Bastards," an expostulation on how the philosophic Enlightenment era got "bastardized" to the point that many offshoots turned out to actually foster the opposite of human enlightenment. Good examples are, the excessive use of numbers and statistics to "prove" something even though most studies cited don't have sufficient sample to actually demonstrate ANYTHING; or the "grey men in grey suits" who run things by committee from afar; or the Enron debacle, in which everyone was trying to prove his own "talent" by demonstrating he could think outside the box, to the point that noone was actually bothering with the box any more.
Ralston Saul's essential point (one I wish an editor would help him make more clearly) is, simply, that the systems which exist in large, organic form, right now, are those systems which are not necessarily best at performing their avowed purpose, but merely are best at PERPETUATING THEMSELVES. When you put it that simply, this comes as no surprise. Does the Catholic church save souls? Or allay poverty, fear, doubt, distress? Who cares! It KEEPS ITSELF AROUND, and many of its supposed "good" policies, often touted as designed to allay poverty, fear, doubt, or distress, are actually quite effective at FORCING poverty, fear, doubt, and distress on its adherents, in effect bastardizing the very POINT of having a church but also -- as a handy side effect -- giving the church even greater financial and human resources.
Finally, I'll declare my own beliefs. I'm a gnostic. No, not an agnostic, a gnostic. Geee Ennn Oh ... without the letter A. I think we have more senses than five, and one is (for lack of a better term) the "theological sense." We "just know" some stuff -- be kind to your fellow man (capital-O Objectivists would actually teach otherwise!); sometimes it works to work hard, sometimes it works better to stop trying so hard; you can't predict the future, but the sun will rise tomorrow, and even if it doesn't I'm a man who can probably cope with it in some creative way; Social Darwinists are at heart angry, unhappy people, and strippers (among others) probably don't like their company, although they (among others) may be mildly impressed with the "social power" they seem to wield with their barking loud voices and harshly determined theories and opinions; life on this world is all we've got, but it's horribly corrupt and muddied and discontinuous and painful; the lot of man is to put forth effort and work and not even always get just rewards for his efforts, so you'd better learn to like the work itself; often a loophole gets you more than the effort anyway; children are horrible little no-necked short-legged beasts with carte blanche to act like assholes and that's why we like them; so are strippers, except they have long necks and longer legs; if you have a certain talent, it's a sin not to use it; if you don't have a certain talent, you'll never develop it no matter how hard you try; killing is bad, nearly always, even when it's a classic "him or me" situation, but I'd probably try to do it in that situation; war is worse, really really worse, and the only way that we end up in one is when we don't have the power to avoid ending up in one, but it's probably going to happen again.
Those types of "just know" thoughts are what gnostics try to find out about. God is in them, somewhere. You can imagine that the early Christian church really resisted the anti-hierarchical approach of allowing one man his own mystic vision. Where would the priests get their money? How would the tribal elders control the adolescent male threats to their power?
Well, I think we're finally in an era of enough economic wealth, and enough worldwide awareness and communication, that many of us are "free" to finally be real gnostics. Not follow a creed, not abandon God altogether, not have a grand over-arching theory, but still be good citizens. The United States is moving slowly away from that opportunity, as fundamentalist zeal grips the power structures again and again. Resist it! Go to a strip club! Vote with your feet, your dollars, her boobies!