Homosexuals have spent a lot of time and effort to justify their behavior and they have a lot of liberal intellectuals as allies in this, generating a lot of self-seving propaganda, studies that do not stand up to scientific scrutiny. Usually, it is the same crowd that prefers to believe in Determinism, so that criminals have no free will, but rather are forced by a combination of genetics and environment to seek pleasure at the cost of others.
Oltmanns and Emery, Abnormal Psychology, pg 10, it is all politics...
EDIT:
If I understand you correctly, this dichotomy you have created leaves out much of what sex for non-reproductive purposes can be.
"Sexual areas" are extremely potent interfaces to the mind of a person. Interaction through these interfaces can be an experience in cruelty, physical pleasure, physical pain, a merging experience, an affectionate experience, a loving experience, a friendly experience, a playful experience, and many many other things. Some mutually exclusive, some not.
Humans are emergent products of evolution. There is no magical inherent purpose to any aspect of us. There are only the possibilities we have, given the parameters of our physical selves.
Non-reproductive sex is masturbation and masturbation does have psychological manifestations. If we limit our selves to being physical selves then we are nothing but hairless apes. The mental self has to become part of the equation of the definition of homo sapiens for our society to become more humane.
It is a good point though, about the distinction between physical selves and mental selves, object and subjects. I believe that the dichotomy between male and female humans has been 'artificially polarized' to facilitate the formation of certain cultures. I believe that human nature is much more of an androgynous state, than many cultures allow for. It was once assumed that there were male and female minds connected to male and female bodies, with the female mind considered as of lesser intellectual capacity. This turned out to be a false assumption.
Still we seem to have difficulty dealing with this artificial polarization of male and female as absolutes, where a subject has no choice between attempting to conform to absolute masculinity or to absolute femininity because of the object of male or female body. However, the human brain contains the template for both masculinity and femininity and most humans would exhibit some traits of both, being mentally, if not physically, androgynous.
Instead adolescents are expected to abandon their inherent androgyny and become 100% male or 100% female, an impossible task. So this perceived failure to become either pure male or pure female leads to confusion and vulnerability in many cases and cause some to identify with the opposite absolute for they failed to conform to the absolute dictated by their X or Y chromosome. I mean if one can't be a Real Man or Real Woman, according to the standards of society, what else is there?
