I have never found Tookie Williams to be a sympathetic figure. Even if he was wrongly accused, a person that deeply involved in the criminal life has to take responsibility for the actions of his comrades in arms if he wants to maintain that he is a real opponent of gangsterism. It doesn't appear to me that Tookie Williams ever left the gang life. He came very far as a person but certainly not far enough to escape punishment. I don't think he should be seen as a hero because to be a hero you have to leave aside thoughts of yourself in order to do the right thing.
That's why executions are so barbarous. They suggest that society only exists for the cooperative satisfaction of the basest desires, rather than enlightened, reciprocal altruism.