There aren't more minorities in games because it just doesn't make good business sense in general. If you are going to risk tens, sometimes hundreds of millions of dollars to develop and market a game, what possible advantage would there be to not try and appeal to a majority audience?
Not only would putting in a minority character instantly limit the potential audience for your game, you are also going to come under way more scrutiny than you would do otherwise with a white guy. Heaven forbid if you're minority character isn't represented in an absolutely perfect light. Businesses don't make games to make art, because 'making art' doesn't put food on the table. Your best chance to see more representation is in indie games.
Not only would putting in a minority character instantly limit the potential audience for your game, you are also going to come under way more scrutiny than you would do otherwise with a white guy. Heaven forbid if you're minority character isn't represented in an absolutely perfect light. Businesses don't make games to make art, because 'making art' doesn't put food on the table. Your best chance to see more representation is in indie games.