It is true that anger can affect our lives in a vast way, depending on how we let it enter the world we are living in; I also think you have listed some great techniques to help calm the emotion when you are placed in certain situations. Considering predicaments, people should, indeed, be angry. There is nothing wrong with anger or any other emotion; however, I once read that emotions can simply be a product of your own thoughts.
For example, the thoughts and mood you are experiencing in that moment have nothing to do with the actual events that are occurring, but rather, your mind becomes the source of your mood based on previous events that may or may not have transpired (previously).
Just something to think about in future interactions/situations, if chosen to!