I'm sure I can't answer your question fully as perhaps HealingMindN could. But here are my thoughts upon reading your question.
In Tai chi, as with yoga and I assume also Qi Gong, some of the unique benefits of these disciplines is the calming effect on the body and the mind. As I understand it they help the body to move out from the sympathetic nervous system dynamics (fight or flight) into the parasympathetic (healing and restoration).
This would be an example I think, of the movements of the physical body "speaking" to the mind and emotions, helping them to calm and balance.