I agree with your points Jonman122, and would like to add that I don't think most people are aware of just how "enslaved" we are to our genes, and as a result, instinctual behaviour. Of course, "enslaved" isn't really the right word to use because without those genes and behavioural traits we would not be human, but there can be no question that sex is a biological trick to make us reproduce through the release of pleasure drugs such dopamine and oxytocine.
Masturbation doesn't result in procreation either, but it still feels good, and from an evolutionary point of view the reason it feels good is because our genes "wants" us to procreate (notice: Our genes are not concious and do not have desires. I'm anthropomorphizing for the sake of explanation).
The ultimate example of the use of sex for something besides procreation are the Bonobo apes (a close relative of the common Chimpanzee). From wikipedia:
'Sexual intercourse plays a major role in Bonobo society observed in captivity, being used as what some scientists perceive as a greeting, a means of conflict resolution, and post-conflict reconciliation'.