Some of you need a chill pill. Beyond the fact that this would cause a PR nightmare, we're also talking about a game based on reality. Stellaris is on another degree of abstraction, no one identifies with the bird people you decided to kill off, but posting pictures on reddit or whatever korean basketweaving forum you may browse about how you slaughtered a culture that is still alive today would be gross.
And furthermore beyond that, I don't know of any instance of intentional, systemic genocide before the 19th century. There were pogroms, cultural genocide, expulsions and enslavement, but not genocide as the systematic killing of peoples. States did not have the capability or need to do this.
