The fact that something is natural does not automatically make it good, or worthy. And the fact that something exists naturally is not a reason to use it. The fact that humans are born with reproductive organs is no reason to use them, at least not for the use they are supposedly intended for by nature. Nature has no purpose, intentions, goals or moral justifications. It is simply an inclusive concept, an umbrella term if you will, for the multitude of phenomena in the world. And in many cases there is a direct and strong moral conflict between what we consider ethical and what we consider natural. There are many phenomena in nature that we morally condemn such as rape, murder of offspring and murder in general. Natural does not equal good. Natural is not a moral justification.
The natural fact that we are born with reproductive organs is not a justification to use them for reproductive purposes. In fact, it is almost certain that even in the view of devout pro-natalists, meaning people who think that creating more people is a blessed and morally desirable thing, there are cases in which reproduction is wrong, for example in cases of carrying genes that cause serious diseases, or people who are subject to living conditions that do not allow them to provide for their children what is considered necessary. Of course, ‘severe diseases’ and what is considered ‘necessary for the normal development of people’ are vague concepts that require clarification, but not for the specific point we are making here: the fact that even devout pro-natalists don’t think that the natural existence of reproductive organs automatically justifies using them for reproductive purposes, clarifies the point that the natural existence of reproductive organs does not provide a moral justification for their use for reproductive purposes.
At least some of the reproductive organs are also genitals, and these also exist naturally, does the natural existence of genitals provide moral justification for using them unconditionally? Of course not. A basic, minimal and unequivocal condition for any use of genitalia is the consent of all parties involved. There is a whole set of values that we use and find necessary to add to the natural biological fact that humans are naturally equipped with reproductive organs.
And since we have already mentioned consent in the case of using reproductive organs for sexual purposes, consent is completely absent in the case of using reproductive organs for reproductive purposes. In other words, no one gives their consent to be created. Consent should be critical ethically, as well as in terms of our normative set of values, but it is completely ignored in the case of reproduction.
In conclusion, the natural existence of reproductive organs does not constitute a moral justification for using them for reproductive purposes. Morality is precisely the tool that requires us to examine what we may perceive as natural and intuitive. After all, if everything perceived as natural were also moral, there would be no need for morality. People would simply act in a way that they perceived as natural, and no matter how offensive the results of their natural actions were, the fact of their naturalness would supposedly justify these actions. It doesn’t, because it is a moral error to infer the desirable from what exists, or even from what is natural.