The primary function of pleasure in sex is to reinforce the pair bond and make reproduction more successful.
When sex is turned into an indoor parlor game, you have massive illegitimacy, children raising children, absence of a strong male father figure, spread of veneral diseases, a rise in crime rates - in short what we have witnessed in America since the “Playboy” Philosophy.
What troubles me is the impact on children. We have several young 'families' on the block. One is a divorced mother of two children (the youngest is 7) from different fathers. She has moved a new boyfriend into the 'nest'. Another 'family' consists of a divorced dad, his 5 year old son and his fiancee. Yet another is a blended family of grandparents, children and grandchildren. These children all play together and often talk to me when I walk the dog. As young as they are, they all know the 'cast of characters' in each other's lives, right down to the proper terminology. None of them has ever experienced life in a traditional family. For them, this lifestyle is normal.