I'm not sure what you're trying to argue, or why anyone would want to limit the choices of other players.
A great many people enjoy immersing themselves in their single player games, and allowing the character to reflect the player is an easy way to help do this. Ergo, saying it is "pointless" is wrong. It may be pointless to you, but I suspect it's because you've enjoyed a lifetime of games whose player characters resemble your gender and race.
As a non-white male, I've never personally felt the need for a character to resemble me in a single player game. I don't play games with the requirement the protag has to reflect me, I play the games I play because I enjoy the experience.
It's funny how you think immersion can be satisfied by simply allowing players to create themselves. If the game environment doesn't recognise a created character then the option to create a character in single player games may as well not exist.