Broadcast media got a little jumpy after the Super Bowl "wardrobe malfunction" incident several years ago. The FCC threatened to fine not only the network, but every affiliate that aired that halftime show. Cooler heads prevailed but that's when network censors tightened things up, including song lyrics.
It still amazes me that broadcast TV is full of shows about murder and other bloody violence, and nobody bats an eye at that, but a brief flash of a nipple is enough to bring down the wrath of the censors. What century are we living in?