The inward elbow fills the void as we load the arm for the outward elbow (major move) and follows the rule of "Never cross the centerline without taking a piece of something." It may also prevent an incidental headbutt as an added bonus. The intent is to get your arm to the other side for the outward elbow. The inward elbow puts that action to use. I would have worded it differently, but I'm thinking that what J. Miller is referring to as "the wasted motion concept" is the notion that there should never be any wasted motion, and not that the inward elbow is a waste of motion.
P.S. - Big guy grabs little guy, pulls and lifts with the elbows flaring as opposed to anchoring as you described is indeed an interesting, outside-the-box possibility to ponder.