The palm does have some bones in Genesis 8 which can give some degree of control. These bones in the palm do mirror pretty closely true human anatomy. The main difference would be in the wrist area or the carpal bones which are a pretty complex series of interconnected points in the wrist. You also need to consider the amount of hidden morphs or (CBM or MCM's) used in something like making a fist in the Genesis series, These help to give the whole hand a more natural look.

When posing feet and hands I generally use a combination of Pose controls and individual bones to achieve the look I am after. Another trick you may consider is turning off or extending the limits on particular bones parameters to give a greater range of movement for those truly flexed poses.

Could the hand and feet be better/more realistic? The answer is definitely yes, but with the caveat that would also add more complexity to realistic posing and further break pose usage between generations of figures.