They've just been desensitized.
First the media used comedy to lower people's guard to the issue. Jack Tripper from Three's Company, and Klinger from Mash are prime examples of using comedy to take the edge off of the subjectand make people feel less threatened. Once that was done, they began working the subject in here and there to make it more visible. Usually doing so on programs aimed more towards young people and shows deemed to be hip and cool. These are classic psyops techniques.