Hollywood has to appeal to the broadest audience, and when it comes to most social and economic issues, America is progressive. Because of that, the messages that are in Hollywood movies tend to be, for instance, pro-environment.
There's such an aggressively apolitical movement in the US that anything that smells of being political - even the term "political" is so ridiculous, when you think about it. The worst part of governing, the political side, is the grossest part, so that's what they call it. So anything that reeks of that immediately gets tuned out by 70 percent of the population.
Obamacare is a private mandate that will drive billions to the insurance industry, much like the auto insurance mandate. Hardly socialism. In fact, it was a Republican plan to begin with.
The easiest time to be funny is during a fairly serious situation. That way, you can break the ice. It's crazy, but even at funerals, people will get huge laughs.
The only way that Hollywood ever skews toward liberal is because part of what we make out of Hollywood involves writers, actors, directors, musicians, set designers, and photographers. In general, people like that are going to be more progressive, more open minded, a little more altruistic.