its not that its a taboo, its just that we're americans and we need pop culture to ocassionally tell us that human sexual interaction is acceptable. after the book isn't popular anymore we'll zip up and go back to our lives of quiet unfulfillment and treating sex like a dirty shame.
'oh a popular book is telling us its ok to have sex? ok, we'll give it the ol' college try then.'
the sad thing is that i'm only halfway facetious.