Some is good and right and necessary. But mainly the Bible warns us against the dangers of anger. You can see from that last warning that anger is very dangerous. If it takes root in your heart and becomes a grudge or an unforgiving spirit it can destroy you. And so the king throws him into jail for his heartlessness.
Anger is very dangerous.
It can take over your heart, turn into a lasting grudge, or an unforgiving spirit, and the result will be judgment. No one goes to heaven unforgiven by God. Heaven is a place given only to forgiven sinners. No one is forgiven who is unwilling to be forgiving. No one goes to heaven who is unforgiving.