I don't fully agree with this change but it does make sense in some ways. First of all most of his organs and all of his limbs and mechanical. From what I hear Revenge of the Sith will provide a better explaination of this change. Shaw there or Hayden both versions provide a message that you can be an evil nutcase and do the most dispicable things but if you redeme yourself in the last few minutes you can spend iternaty in peice. Putting Hayden there doesn't do anything for or against this very wrong message.