In Fiction Land, it's easier to come Back From the Dead than it is to get rid of a scar or recover a lost limb. While it's true that Beauty Is Never Tarnished, and it's a Good Thing You Can Heal means it's highly unlikely for serious injury to happen or leave scars in the first place, there are occasions when a character can't count on that to save them, and they get badly injured in the line of duty. These injuries can be scars, lost limbs, or losing an eye... and the wounds you would expect to see in Real Life aren't reset or retconned away. Often Achey Scars.