When a person is overwhelmed with emotions, fear, anger, their own safety and the safety of others can be at risk. I'm not saying get rid of emotions entirely. But the human brain can be so dominated by emotions at times that it screws everything else up. 100,000 years ago, it wasn't so terrible if someone flipped out. But now, with everything from guns to nukes at our disposal, it's a different story. The structure of the brain is an impediment to progress.