It's really useful to understand some things. Like stress reactions, how humans deal with change, group behavior and some other things that I don't have my books in front of me to reference.
But it's always reported as WHAT THE DICK WANTS AND MAKING BABIES! It's always heternormative. It's never about studying the full range of human experience. Homosexuality is not rare, nor is gender fluidity, and all these things contribute to sustainability and propagation of the human species. It's far more complex than just making babies.