Why super-powers should be all or nothing in sci-fi

I have never completely understood the latest sci-fi fixation with ‘super powers’, where the main protagonist is just some ordinary person who just happens to be able to go invisible, or read minds, or teleport (but not all three). Inevitably this singular ability then becomes the ‘gimmick’ on which plots are hung. To which I … More Why super-powers should be all or nothing in sci-fi