The amount of polemic going up is probably because creators are worried with the way things are going that more people just wanting to sit back and not think about the world’s problems.
Now all of those formats (ESPECIALLY books) have always had ones that were QUITE political, but there was also a lot of content that was just for relaxing and escaping from the reality of the world which has always sucked. Recently, it seems like they've started really ramping up the political content in many movies, shows, and games and some people certainly enjoy that, but then again...a lot of people don't like being preached to in every aspect of their lives.
Looney tunes, Animaniacs, some SNL skits, Blue's Clues- these all had that lack of present day political stuff, but even something as light as The Drew Carey Show had themes about stuff like political correctness in the office place, and cross-dressing/genderqueer folks.