Absolutely they have. CBS News, ABC News, And NBC News all skew left. CNN and MSNBC slant heavy left. The late night talk shows that used to be about comedy have been taken over by liberal mouthpieces. Stephen Colbert, Seth Meyers, and Jimmy Kimmel are nothing but liberal shills. Jimmy Fallon tilts left, but at least tries to keep comedy in mind. Then you have shows like The View that claim to be balanced because they have one conservative that constantly gets shouted down by Joy Behar and Whoopie Goldberg. You ignore all of this because they fluff you up with what you like to hear, then call out those who say things you don't like.
And that's just TV. Printed media may very well be worse. You see what you want to see, which, apparently, isn't anything close to reality.