'Invented Discrimination'

It's a recurring trend in games that clearly touch upon very important issues such as racism, religious discrimination, etc. for them to obfuscate their commentary by having humans in general being racist towards an invented race or group, such as in Dragon Age: Origins where humans are racist towards elves. It creates a situation where the writers want to say "Look! Here's racism! Isn't it terrible?", without actually tackling the issue in a helpful or interesting way. Given that games are an interactive medium, where the player has choice, has agency, there is a lot of opportunity for engaging the player in the issue in a way that non-interactive media cannot.

As an example, in Fallout: New Vegas, the player can choose the gender of their character. There is a particularly sexist faction in the game called Caesar's Legion, and if you chose to play as a female character, they react negatively towards you. Even a minor part of their camp is restricted from you on the basis of your gender. I personally found this to be a very powerful way to make a statement about sexism, but things like this are all but unheard of in games. Why is this? How can it be avoided? How do we talk about these issues using the strengths of the medium?