Think about it: when we have expectations, and things don't go the way we expect (which happens quite often, as we're not good prognosticators), we are disappointed, frustrated. It's our expectations that force us to judge whether something is good or bad.
When you expect something of a friend, co-worker, family member, spouse, and they don't live up to that expectation, then you are upset with them, or disappointed. It causes anger. But what if you had no expectations — then their actions would be neither good nor bad, just actions. You could accept them without frustration, anger, sadness.