To be fair, to fit orcs and imps into the game now is a bit late. To make them feel right you would have to add specific dialog to a few NPCs along the way, which would involve digging up voice actors. There would also be some balancing issues to figure our what the racial traits would be. As there would be no origin characters for the races, they would feel left out as well. As such, I don't think it is worth all the work to add them into the current game. However, I do agree that adding them into a future game to play would be fantastic.
