For the most part I would agree, but there have been cases where the droid's extensive programming has allowed it to expand its own objectives and programming. The major case would be IG-88A, who did just that and killed the ones that built him when they tried to shut him down. He wanted to start a droid revolution, and upload himself into the Death Star to accomplish it.
If we are speeking of the fantasy world you are totally correct but my ideas about this is based on the real world. There newer was a droid-robot or any kind of AI in human history to turn back and kill its creators. Such a decision requires a "mind" and that kind of mind has not been created yet. Until an AI such as B166ER(the very first one started the Matrix world of Artificial Intelligence) been created, my toughts about this will not change. But I have to tell you that no one in the world wants that to become real more than I do. A robot purely acts differently than its programing. This will change everthing.
Even a human being can not act different than its programing. Everyone may think that they have free-will and do what ever they want but this is not correct. You have boundaries that were set by nature, birth and other people. AI has such boundaries in itself. Can anyone really answer the question of "why someones life should be saved?", what for any AI should to take someone's life? Even we are being programmed by our parents, society and other factors. But that does not keep us from creating something with great resemblance to us. Almost all religious books has that "god created us on his own looking" thing. Don't know if we were the ones wrote those books or god himself(if such thing exists) but it is so apparent that we are willing to create "something" in our own looking. AI is a product of such tought. While playing god we are bounded by our own image. Bec. that no human being is really free, nothing we created will be.