The one thing all the nominated films for Best Picture have in common are their strong social themes. Some critics have labeled them "Art House Films," but they are much more than that. The theme for the leader of the pack, BROKEBACK is homosexuality, set in the time of 1960's mores. [I never use the term "gay," if I can help it, because using the word gay that way is a perversion of the original meaning of it, and people who don't know history misread titles and statements such as "The Gay Nineties," "When Our Hearts Were Young and Gay,' etc.]The theme for CAPOTE is social violence, but the main character is a homosexual, as was the real Truman Capote who wrote the book In Cold Blood about the true-life 1959 murders of the Clutter family in Kansas. MUNICH is about terrorism, specifically the terrible incident during the 1972 Olympics in the city of Munich, Germany, and its aftermath.
GOOD NIGHT is about those dark days in 1950's America that have become known as the McCarthy Era, when civil liberties were at the greatest risk of being constitutionally revoked in any time prior to the current Bush Administration. CRASH is the only one set in contemporary times. This Lions Gate Film, according to its Web site, "Takes a provocative, unflinching look at the complexities of racial tolerance in contemporary America in this case Los Angeles."
In other words, they all deal with contemporary social problems set in prior times, except for CRASH. It is much safer to deal with today's problems that way, because we can put them in a box and tell ourselves we are not involved, until the day our lives and the social concerns -- sexuality, murder, violence of humans against humans in general, authoritarianism, civil liberties, racial tolerance, etc., collide.