The force, like all powers, would be a two edged sword. Action is not a bad thing. Neither is non-action. The master begins to understand his place in the scheme of things. The Yin-Yang is a symbol that is equal parts white and black, and even the black has a spot of white, and vice versa.
Nothing is purely dark and nothing is purely white.
There are corruptions in either. Luke has his dark side. He wears solid black clothing. He kills a LOT of people, because he must . Ethical codes exist and are important, but like all things they will break if held too rigidly.