In a six minute interview with Joystiq, Irrational Games boss and lead on BioShock Infinite Ken Levine talks about why it is important to not be afraid of using topics that some might consider controversial as vehicles for a story. In BioShock Infinite, Levine has weaved a narrative around a number of belief systems and ideals, and all of these things come together in the floating city of Columbia to create tension and drive the narrative.
The game touches upon such topics as the idea of American exceptionalism, how the pseudo-science of Eugenics was used in the early part of the 19th century to discriminate against different races (and those with physical and mental handicaps), the workers' rights movement, and plain old racism.
Levine notes that he doesn't want to shy away from these kinds of topics. He also says that he doesn't want to add characters of a specific race, gender or sexual orientation just for the sake of adding them.
Levine compares not hiring a person based on gender, race, and sexual orientation to employing (or excluding) characters in a game based on the similar criteria. He says that employers should hire based on skillsets and not on the race, gender, or sexual orientation of a person - just because they have some sort of personal bias, Levine also says that he uses characters that are important to whatever kind of story he is trying to tell as opposed to putting someone in a game for the sake of having them there to be a "positive force" represented by race, gender, or group.
You can watch the whole interview on Joystiq.
BioShock Infinite is set for release in March 2013.
Update: Adjusted the latter part of the story for the sake of clarity.