Popeye's nemesis, Bluto, was also pretty simple. In his case, he wanted to win Olive Oyl for his own, so he possessed a bit more reason to oppose hero Popeye. But Bluto's obvious role was still to be the villain who provided conflict until Popeye defeated him with the aid of spinach.
Current events provide authors with a living example of this truth. When Vladimir Putin sent military forces into the neighboring country of Ukraine, the West saw that as a clear violation of another nation's boundaries, a cheap land grab at a time when the political situation next door was confused and uncertain. The temptation in the West might be to paint Mr. P as the ruthless villain who knows he is evil, enjoys being evil, but tries to cover up that nature by posing as a normal politician. However, if you were penning current affairs as a political suspense novel, you would want to create more depth in the man. For instance, picture this scenario: you are the leader of the world's largest country. Your capital is full of bustling life. New businesses are starting there. New buildings are going up. Yet, countless citizens eke out a simple existence. Alcoholism is rampant. Many citizens' homes across the countryside still have outhouses instead of indoor plumbing.
See the difference? Even Adolf Hitler--one of the most despised characters of the twentieth century--did not see himself as a Snidely Whiplash, going about to do evil for the sheer glee of evil. Hitler had friends. He had a girlfriend in the person of Eva Braun. His citizens adored him. They saluted him in droves. After the embarrassing defeats of World War I, wasn't he the man who was finally bringing the glory back to Germany? True, minority groups would get swept aside, and other nations did not like the process, but a powerful new Germany was rising from the ashes....
Point of view is a powerful tool. When an author can enter the head of his "bad guy" and see how even a criminal can imagine himself to be the good guy, that author is ready to paint his characters with extra depth.