Out of curiosity, how familiar are you with organic chemistry, sexology, genetics, evolutionary biology, anthropology and the intersection of these fields? Because, as just about anyone who studies sexual mechanisms within them will tell you, sex is something that "just happens" in exactly the same way anything else does, including covalent bonds: there are natural laws at the most basic level that make it all happen, extremely complex interactions between chemicals/chemical attractors being just one extremely important factor. Trying to will certain types of sexuality away will not work: you might as well ask the sky to fall. Any special pleading about "cultural mediation" is just bog standard cultural theeree humanities waffling. You can say anything you want about it, but until you have some evidence, it's just talk. (Btw, a Northwestern professor demonstrated that there's actually a negative correlation between porn consumption and rate of rape: counties with the highest per capita consumptions of porn and subscriptions to porn sites actually had the lowest rates of rape in the U.S.)
"Sex positive" is not a posture, it's an anthropological term used to describe cultures that do not describe sexual behaviors outside of monogamous heterosexuality as "sinful". I don't believe in "sin", so of course I'd like to see these sorts of designations, and the related cultural imperative toward heterosexual marriage and monogamy, go out the window. The only 'committment' I have is to refusing to impose some sort of phallogocentric bullshit slash Ceiling Cat decree on anybody... and as a sideline, I think dismantling patriarchy is pretty important, too. By the anthropological definition of term, if I succeed in these goals, my culture will become "sex positive." Would be wonderful, but again, not holding my breath...
Did I say anything about being "tolerant"? No, I did not. There are many things we shouldn't tolerate as a society (including rape, child molestation, sexual assault, sexual harrassment, etc), and this is already up for negotiation, discussion, and legislation. There's plenty to critique in our culture, but there's little to critique about the impulse to have sex per se. The critical element of feminism has always been based on a criticism of patriarchy and of the ways sexuality exists as a function of patriarchy, not of sexuality as such. It's proven that outside of patriarchical cultures, the tendency is toward increased sexual freedom and less sexual hypocrisy/slavery/injustice. This is not a difficult concept, and it's really not up for debate. It's clear where we should move, then, if you dislike rape and the oppression of women and sexual minorities: away from 'sex-negative' patriarchy and toward 'sex-positive' matriarchy.
Basically, moral approaches to anything, but especially to sex, put the cart before the horse. The goal should not be to "critique" sexuality itself as if that will somehow change human behavior. Sex is a psychologically (not an ethically) motivated behavior. If you want to change the behaviors that have negative consequences, you have a lot of work ahead of you; first you'll have to figure out what this means, what these are, and how to do this, but then, most importantly, you'll have to change psyches. If you want to change psyches, you'll have to make largescale economic and political changes that have nothing to do with asking people to criticize their own sexual impulses or drives.