What I don't understand is why people keep asking about other games like that is a profound statement of DnD. "You don't dribble the ball in baseball do you?" Isn't exactly a good retort for changing the rules for dribbling for Basketball.
And, I'm also getting annoyed with this continued pattern of "Well, players can just adapt or play a different game." Yes, but the DM can also run a different game. That is also a valid option.
DnD has been a game about Fantasy races since basically the beginning. This is a core part of the game experience. There is a reason the "joking insult" is that DnD is a "Magical Elf Game" instead of a "Fantasy Kingdom Simulator" or "Historical War Game" A large part of the appeal of DnD is the vast array of races, both that you play as and that you fight. Comparing it to Call of Cthulu, which is based on a series of novels and stories about Humans and Cosmic Horror, is just not a good argument, no matter how you try and make this about "why is it okay for the company to make these restrictions"