Anger is a major emotion that can guide people, or ruin their lives depending on the cool-headedness of a person. Anger, just like any emotion, influences decisions made in the moment and inhibitions one might have, and this can be either a positive or negative way depending on your control of your emotions. While being angry is often seen as a negative thing, anger must be expressed and let out for a healthy, low-stress life, and is in fact very useful if used properly.
The only reason anger is seen as bad is the consequences usually caused by an overly-upset person making irrational decisions, and while this does happen often and can lead to major problems in life, having anger under control is not only good for those around you but useful for personal gain. Anger leads to rough decision making, but keeping a cool head allows one to use anger as a motivator, a problem solver, or it can be used to form logical arguments when it could otherwise be used for violence or or less-professional arguments.
Anger often makes people, for lack of a better term, argumentative. This, however, is the best part of anger as the will to argue can be controlled to form strong, logical opinions. While usually anger leads to irrational thought, if one directs their anger into a mature solution it not only makes you seem smarter, more composed, and emotionally stronger. This makes anger into something more resembling a tool rather than a weapon.