The principle for Day #68 on the 101-day book report says: "Everyone that comes into your life is valuable."
Conflict is at the heart of any good story. It keeps you flipping the pages.
I think that's why antagonists, bad guys, and petty tyrants all have roles to play in the comic book of our lives. They make us miserable. They make us suffer. But without them, even a superhero soon discovers that he's his own worst enemy.