Try triggering the anger of some and what you may get is a reminiscent of each and every problem they had dealt with you. No likes to be reminded of their past mistakes. Such people are those termed by Eckhart Tolle (http://en.wikipedia.org/wiki/Eckhart_Tolle) as 'Pain Bodies'. These people, in simple words, are able to accept a sorry but they can never forget anything that has hurt them what more the people that caused it.
These people termed as 'Pain Bodies' at many times are prone to merely unleashing their anger rather than reasoning out on an argument. They prefer to welcome back past memories that had burdened them as a way of excusing themselves from having to deal with the problem.
Why this is not good? Well, first of all, anger is not good. Next, we must be able to learn from the past and move on to fully live in the present moment. It is not only of the well being of ourselves that we have to care for ourselves but also for those who are living in our surrounding.
Anger can leave scars but it is only with love that one can bring about the changes he/she desires. What can we gain by throwing out words or raising our voice to state our feelings? Regardless of how hurt we are, anger must be managed well.
It is not to say that anger must never be seen 100% from ourselves because we have to have reached much enlightenment in order to be anger-free. However, the level of anger that we portray must be controlled as to clearly indicate how terrible a problem or a person is.
We must pull ourselves to remember at all times that when we are facing a problem, we must try focus at the content of the problem. Sometimes we may have to accept things the way certain things is meant to be and sometimes we can fix it for the better. There is only these two options and anger should not be a part of these options.