Banning those things on children-specific channels, and adding warnings before those contents are aired on non-children specific ones, as well as making parental control devices widely available.
A.there are no children specific channels that the govt has any control over (the FCC only has power over broadcast stations, not cable), yet those channels still manage to not show boobs and (realistic) violence.
B.the warnings are here and had nothing to do with govt intervention (thank Og)
C.the govt did force the parental control devices on new TVs, costing us all money and only being used by a tiny fraction of people
Also, violence on TV does not translate to violent children or adults.