Humans are largely driven by a combination of primal animal instincts and emotional neediness; the latter is also a primal animal instinct, to be sure, but one derived much more from infant helplessness than the need to reproduce.
These are sensations brought on by the immortal soul being tied to the animal flesh. Certainly, the soul has no inherent “need” to reproduce; these are aspects of the animal flesh.
A person much more connected to the soul, and less to the flesh, will have less of a need for actual physical sex. As humans evolve, there is collectively less of a need for physical sexual relations. This is because evolution involves a gradual moving away from the animal flesh towards the soul-state.
There is another use for the physical act of sex, and that is esoteric. This historically used to be highly guarded information, only available to the elite and the initiated. Some of the traditional taboos regarding sex were for this reason.