Anakin is by definition a mass murderer. He killed many sentiment beings in under 24 hours (if he had killed them over time he'd be a serial killer) and he slaughtered the defenceless. He is a mass murderer, and you can't argue that fact- you may understand his reasons (I know I do) for doing it and you may agree with him but that doesn't mean he didn't do something morally wrong. GL wanted you to empathise with him and at the same time realise that it is a tremendously evil thing to do. Lucas himself has said that with the PT he was trying to understand how someone turns evil- people aren't born that way (innocent little Ani) so how do they become people like Hitler, Stalin, Atilla? The do it in small steps- this was one of his first steps to becoming Vader and becoming evil. the PT is about the descent into hatred and evil, the OT is about being redeemed by your children- he's a big believer than the sins of the fathers are redeemed by the children. The only issue I have with it is Padme's lack of reaction. While she may have understood his reasons don't you think she would have been a bit (actually a lot) perturbed by his actions at the same time? Lucas dropped the ball there, he took a very powerful scene and lessened the impact by the lack of reaction from Padme.