In the novel Lord of the Flies, why did Piggy die?

In Chapter 11, Piggy tells Ralph that they must visit Castle Rock to get his glasses back. Piggy says that he will simply walk up to Jack and say, "I don’t ask you to be a sport, I’ll say, not because you’re strong, but because what’s right’s right" (Golding 246). Piggy naively believes that Jack will be understanding and sensitive to his needs. Piggy does not comprehend the utter savagery that completely personifies Jack. After their assembly, Ralph, Piggy, and Samneric travel to Castle Rock to confront Jack. Piggy then holds the conch and begins to question the savages about why they are acting uncivil. Piggy says, "Which is better—to be a pack of painted Indians like you are, or to be sensible like Ralph is?...Which is better—to have rules and agree, or to hunt and kill?" (Golding 259). Piggy's comments upset the savages and Roger rolls a massive boulder down the cliff that ends up killing Piggy. Piggy could not see the boulder rolling towards him and did not move out of the way. Piggy died because he thought that he could reason with Jack and the savages. Piggy not only put himself into harm's way but incited Jack's band by making an appeal for civilization. Roger also took pleasure in harming others and was excited about the prospect of murdering Piggy. Roger is sadistic and was more than happy to kill Piggy.