There is value in anger in the same way there is value in volatility: When both are handled properly, they help us advance to where we want to be. Traders learn how to handle volatility so that it becomes their friend. As people, most of us don't have that kind of training for handling anger.
We only need to deal with anger when it comes our way, Part of that is defining lines not to be crossed and making sure they don't get crossed, then letting the line crosser know we were serious and follow through. If we do this enough times (the fewer the better), then people know not to cross our lines.
If we can control our situation, then we can do much to minimize the times we are angry, so we don't have to worry about anger. If we cannot control our situation, then there is no point in getting angry for situations we cannot change, so here we don't have to worry about anger either.
The bottom line is that we work toward finding happiness as best as we can, but we have to deal with anger effectively when it comes our way. This is the part most of us need to learn how to handle better.