Anger is the only emotion that shows enough displeasure for the sinful act committed. Anything less would be tantamount to approval. The recipient knows EXACTLY what he/she did wrong. Also, knowing this from childhood, anger from the parent for some wrongdoing makes one think twice about repeating the act. It is a stop-dead-in-the-tracks type of thing.
Uncontrolled anger serves no good purpose. That anger is not channeled, is wasteful and it hurts feelings and confuses the person(s) at the receiving end. They feel justified in being hateful in return because they know they did not deserve to be punished.