This is possible, but adding more joints would cause some users to lag very badly, and they wouldn't be able to play. Many of these ideas have been suggested, but are just not gonig to follow through because of the outcome.
A model like that would raise the poly-count significantly (from some hundreds to thousands min as far as I can see) and through that also the calculations needed.
Plus at least the middle body would need some kind of "flexible skin" instead of simple IK like it is now. All this together would raise CPU/GPU-specs needed to get it work.
Beside that the complete physics model have to be rewritten, masses are actually based on the size of the objects (correct me if I'm wrong) and a new model like that would completly kill this.
1)Texture messed up
2)Flames messed up
3)Hair messed up
4)Gradient and force messed up
5)So everything is messed up