I did experiment a bit with using the Grasshopper cage morph stuff I posted here for this.
I warn that this is far from a conventional skeletal posing/animation workflow like you might use in Blender/Poser etc. and it is still far from easy - you have to manually move the cage points in the right way to not stretch or squash the form too much - and for very dramatic changes in pose it will probably break down.
Anyway, here it is if you want to try:
deformable_hand.gh (4.2 KB)
deformable_hand.3dm (401.5 KB)