And you fail to understand Anakin's motivations. He's motivated by power and that motivation is fueled by fear of loss. He wants to be all powerful and the way to become all powerful is to choose the dark side, because it will give you what you think you want. Which is control. Control over everything and everyone. Including control over life and death. The Tuskens hurt him by taking his mother from him, so he hurts them by taking their lives from them. He will lose his wife and has been told that the key to saving her lies in the forbidden teachings of a religious group that is targeted for termination by his own people. And in the battle between his wife and the Jedi, he will choose his wife over the Jedi. He will kill them all in order to keep Palpatine alive so that Padme will live. And as the films have long pointed out, a Jedi can only become more powerful by surrendering to the dark side and killing indiscriminately. This is why the Sith provoke the Skywalker men into using the dark side in order to destroy them, telling them that their anger and hate makes them powerful. That it gives them focus and they can feel stronger as a result. Anakin says that he feels more powerful after all the killing. And we see Luke have a look of exhilaration both times he cuts loose with the dark side. Anakin is only saved because he lets go of his desire for power. He realizes that he could have saved Padme by not embracing the dark side. He realizes that he always had the power within himself. He realizes that he can save Luke as he is and not as he wanted to be. When he struggles between the light and the dark, he is struggling between compassion and passion. Between selflessness and selfishness. If he stands by and lets Luke die, he is choosing to be greedy and selfish. He is choosing the dark side over the light and his desire to be the Dark Lord of the Sith and possible Emperor of the Empire. If he saves Luke, he is destroying everything that he has ever wanted. He is giving up his life for his son's. He is giving up all of his goals and ambitions in life. He will destroy Palpatine not for ambition, but for unconditional love.