It's true that you can change the look of michael and vickey in a lot of ways, but you are limited the mesh shape - Once you do enough changing of the mesh - the other basic morphs like Phonemes, open mouth, smile, raise eyebrows... etc. start to conflict with the morphs you've made, creating weird creases and faces you don't want. The advantage here would be variety at a cheep cost with even more possibilities for working faces.