Wing Chun is to train the mind to control the body by operating and responding in the moment, in the present, with no preconceived notions, to all stimuli and respond to those stimuli with an appropriate response, whatever that response may be. Anticipation will place you in the past by predicting a future event and missing the present moment. The objective is always to clear the mind of chatter so that you can achieve the highest level of awareness.
Siu Nim Tau, Chum Kiu, Biu Gee, Mook Jong, and Chi Sau are all moving meditations when performed correctly. The hands and postures of the forms, Chi Sau etc. are nothing more than tools to create an environment to reach the Wing Chun State of Mind. Once that mind state is achieved, the hands and postures are irrelevant because all movement after that is Wing Chun when guided by the mind. When you strip it all down you will see that this state of mind is the ultimate achievement of Wing Chun. When this state of mind translates into fighting, it is then you are actually using Wing Chun. Once this state of mind is achieved the theories and representations become matter of fact and not the governing rule.