Yes, I agree, there seems to be this negative stigma attached to sex, even moreso than violence. I see my brother's friends (12-13 yrs old), who are allowed to play M-rated video games (who can blame them, they're fun
), while being forbidden to watch movies because of mild sexual content.
This being said however, I don't believe a child should be exposed to pornography until they are around 12-14 years of age, depending on their maturity level. Kids younger than that often don't know how to seperate when they see in the media from reality. I'd probably also stress that a lot of the more hardcore stuff, such as the Double Anal Fisting movies promised in several recent spam emails I've received, is verboten. Consensual sex is fine, as is nudity.
Well, those are my thoughts.