Genetic diversity matters greatly, which always made me scratch my head over people who were not into interracial coupling. Mother Nature desires this as it maximizes genetic diversity with a catch, it requires both partners to be diverse but also be smart too (STDs).

She wants diversity and smartness, and the vocality of hearing pleasure should always be something to boost the confidence of the mates that each partner is with.

Win-win, but very scary for those of limited intelligence and confidence ...