st. james thought:

     I’ve read in old interviews with Milt Khal’s fellow animators that he did the swaggle to purposefully show off. Moving the head in 3-d space is an exceptionally hard thing to do but Khal upped the level of difficulty to a place many animators wouldn’t go.      Not only are they all doing the swaggle you’ll notice they are all TALKING while they are doing it. This is back in the days where you had to use a timing sheet to pace your animation and a head swaggle doesn’t work if its too slow or too fast so he had to figure out the right speed so it looked natural while the character finishes what they have to say while not interfering with the distinct mouth shapes.       Not only did Khal do it without any shifting weight problems or timing issues he would often do it while moving the rest of the body. This isn’t his signature move just because he was good at it.This is his signature move because he was one of the only people skilled enough to DO IT AT ALL.