I think this is another example of lies being necessary in order to live. Most people need to have sex ("bed is the poor man's opera"), yet they do not (yet) want to have children, or do not want to have a child every time they have sex. Thus sex, for them, has, in many cases, become some kind of a snack: one does not eat a snack for its nutritional value. Yet this does not mean that food is not naturally only a means to nutrition. Also, I think most people do not have the philosophical integrity to see the truth of what I'm saying here: that sex is only a means to procreation, and that it is pleasurable in order to tempt us to have it. Yet there is one way to "save" people from my verdict: the distinction between short-term and long-term considerations. On the short-term, regarding sex, a man wants to impregnate and a woman wants to be impregnated. Yet they may not (yet, or again already) want the consequences of that impregnation.