You seem to forget that Larian needs to make money. That means keeping development cost within reason and releasing a product that the majority of people of the TARGET AUDIENCE will like/buy.
And no amount of philosophizing will change that. Welcome to the real world.
All variety of choice that is offered improves the worth of every option.
Probably 90%, if not more, of people will defend the tieflings, only a small % of people will actually kill them, but the existence of that choice makes it worth something in contrast, if the plot was railroaded for us to do what the majorirty would do, it would not be as satisfying. Same for options with appearence and aesthetics, your personal choice matters.
By the nature of the genre - RPG, it thrives when it offers unique niche options, otherwise, what is the point of a choice if the only choice that is offered is what majority would do anyway, you can just make a linear adventure game then with a set protagonist Tav with a vault dweller appearence.
PS. This logic in general is also just so funny to me. -Hey, what kind of game do you want to see? -The kind that will make money!