This statement is simply, flatly, insane. If you think the propagation of the human race is "an unfortunate side effect" of your pleasure, you're too far gone even to reason with. You are so deeply into redefining reality to be what you want it to be, you have no connection to reality anymore.
I am a being with free will. I have the right to define sex however I choose.
Can you define mathematics however you choose? Chemistry? Physics? Hardly. As I say, you think you make up your own reality. Sanity is conforming one's behavior to reality, not engaging in continuous attempts to declare that you can reconstruct reality they way you want it to be.
(Shrug) Procreation can be the purpose of sexual intercourse, but it does not have to be. The inability to control one's fertility naturally is a flaw of the human body. Modern science has given us the ability to control that flaw.