Each side of human face left and right, has 16 muscles total 32, Muscles of expression, because their contractions or relaxations give rise to a human expression. Examples are anger, joy, surprise, contempt, sneer, satisfaction cynicism puzzle, pain mild or severe etc and various shades of expressions in between.
Having mechanical devices built to display full range of human expression may not be an immediate need, but perhaps later robotic developments may cater to such human anatomical and physiological "assets".
Parallel to such technological advance is begining of the impact upon individuals who will inter act with machines. No one can prognosticate the psychological outcome. But the "advance'' in all probability would not be curtailed.
What is good for the society at large??