Why couldn't Nebuchadnezzar have a benevolent empire?
No human possesses the love and graciousness of God needed for benevolent rule. Nebuchadnezzar, like other great dictators, was a despot and totalitarian, having no concern for his subjects while keeping all decision-making within himself. Therefore his empire could not be benevolent.
Les explains that had Nebuchadnezzar been a benevolent type individual, had he had the love and the graciousness of God, he could have had that kind of an empire, but no human has those kind of attributes. So Nebuchadnezzar, like any other great dictator, was a despot and a totalitarian. He had no concern about his subjects, but his decision-making was within himself. This matches the political pattern of Daniel 2, where the great empires became weakened by the number of people involved in decision-making and were inferior to the one before politically.