Too risqué for the radio?

Today while rocking out to Rhianna’s S & M on the radio I thought about what could be considered too inappropriate for popular child consumption. Rhianna sings “ I may be bad but I'm perfectly good at it/ sex in the air I don’t care I love the smell of it/sticks and stones may break my bones but chains and whips excite me.” From previous experience, my nieces, nephews, and 3rd grade campers all listen to popular pop radio (like z100). When songs like Katy Perry came on to the scene with I Kissed a Girl it was semi amusing to see 7 year old girls singing about experimentation, but also a tad inappropriate. When my nephew sang Brittney Spears If You Seek Amy I was a little sad (after I finally realized what was wrong with the song). My problem is, yes people are censoring songs left and right, like Cee Lo’s F*** You, but the topic of sex is apparently not worth censoring. It makes me laugh thinking about how back in the day Elvis was considered too risqué because he exuded sex and used his hip thrusts to prove it. I wonder what my grandmother’s generation would say about Lady Gaga’s constant crotch grabbing and studded bikini outfits. My question is, when do we say these things really shouldn’t be out there for popular consumption, and am I the only one who feels this way? If you wouldn’t take your child to a rated R movie which is rated R for nudity, why is letting them watch music videos or listen to risqué lyrics appropriate?