@VarsityxNerd Because he was still young, and he let his emotions get control over him. But your right Padme would have lived, and Anakin maybe would have found his way back.
@VarsityxNerd The unmasked vader looks older because his body hasnt seen light in like 20 years! Plus it also has to do with the fact of him getting burned. His wounds didnt have much time to heal properly with the rubbing of his suit.