In the big picture, man is civilised and intellectually driven, with the development of rules and laws to seperate the species from the rest of the animal kingdom...
As a result, look around you - no other species enjoy such trimmings of life of their own creation - but, they have sex without rules and laws.
Man has come too far to enjoy the basic primeal needs, and nothing else - but one has to agree, it might be a nice alternative, from time to time.