@SunSun - Very true. In manga, anime, games, and many other mediums, nobility tends to play a very antagonistic role specifically to appeal to the largest consuming demographic -- which obviously consists of "commoners"; or rather, the lower and middle class. It's a very easy enemy to create that is relatable to people when juxtaposed with the divide sometimes seen in real life between the rich and the poor.
However, in real life, the trope-like behavior of nobility seen in these stories would very much not serve them well at all. Not only because it would make their people feel disenfranchised, but also because such malicious behavior would make them a target for assassination from their fellow nobility as well. A person in their position with such blatant greed, who is openly untrustworthy, and has clear ambitions to attain higher status with more power would be disposed of rather quickly. It wouldn't just be to stop them, but also as a preventive act done for the sake of self-preservation.
Really it's all a matter of properly maintaining the status quo. A proper balance of benevolence and cruelty. Nobility and even modern day governments would much prefer to have the people feel like it's other people that are the "bad guys", rather than to take on that role for themselves. The instances where this balance has been broken in the past, whether through too many good, or bad intentions, has lead to many things; such as, insurrection, revolts or even revolution to name a few. To keep with the topic at hand, one could easily see the real world consequences of a corrupt aristocracy through the French Revolution, and some of what followed. While it's definitely a bit more complicated than my implications, I'd say it's a somewhat fitting example. It's something that has valuable lessons that many still learn from today.
Anyway, I really enjoy reading and learning about people and history, so talking about this was kind of fun. Sorry for the long post.