I think that the "deadness" that some people have complained about with the prosthetic could be solved by adding a bit of red around the edges, though. Part of what gives out skin its color is that it's got red stuff underneath it. Also, I think that the prosthetic having living tissue over it is a much cooler sci-fi concept than simply being covered in a layer of life-like plastic. If such a polymer existed in the Star Wars universe, I'd be very shocked that they didn't already have it at the time of the Clone Wars. The flesh covering could also hint that the clone wars opened up new opportunities in regenerative medicine, since it's a field closely related to cloning-- that would explain why Anakin had to settle for a metal prosthetic, wheras only 20 years later, it's possible for someone to get a bionic hand that looks like the real thing.