Why is it important that Stevens is a butler as opposed to a Lord or a Duke of some kind?
I think that the most critical element of Stevens' character is his adherence to what he sees as his duty. This is reflective of someone who "follows orders." If he were a person of power such as a Lord, he would be the one giving orders. His characterization of someone that follows these precepts without reflection or thought helps to bring out his own sense of regret and helps Ishiguro to bring out the danger in blind obedience without a sense of questioning. Stevens' role in the novel is to reflect the danger of following the path that others have set without reflection and a sense of voice in the process. Stevens' adherence to this notion of tradition and duty is echoed with his role as a butler, as one who follows orders without much in way of autonomy or being the agent of action. Ishiguro's depiction of him in this way brings out how individuals who fail to reflect or speak out over perceived injustice suffer greatly in reflection for their actions. If Stevens were in a position of power, than it is less about obedience to another individual's precepts and more about his own decision. What makes Stevens such a powerful character is that he was in the position where he was compelled to follow elements such as tradition and honor. However, the full dimension of his character is revealed when he recognizes that as limited amount of power he had as a butler, he still could have spoken out and used his freedom a bit more to find happiness in his being in the world. It is to this end where Stevens' condition of powerless is one to be revealed as one that still has power.