It's a uniquely American prudishness.

It's a uniquely American prudishness.  You can write the most detailed, vivid description of an ax entering a skull, and nobody will say a word in protest.  But if you write a similarly detailed description of a penis or a vagina, you get letters from people saying that they'll never read you again.  What the hell?  Penises entering vaginas bring a lot more joy into the world than axes entering skulls

-George R.R. Martin