Flying Crane
Sr. Grandmaster
I agree that forms alone are only one tool in a toolbox that needs to contain several. Big movement itself does not automatically mean powerful punches. However, big movement is a training mechanism that helps you understand how to connect the body parts and make it fully connected, full-body connection in your movement. That can lead to very powerful technique, which still needs to be trained on a heavy bag or other striking tool.Obviously I am not an expert, but From years of punching, I don't think big movement implies hard punches. I don't think people can tell how good a person punch by just doing forms, get on the heavy bag and one can tell very fast how good and how powerful the punching is.
Also, the more exaggerate the shoulder rotation, the slower the punches are as it takes time to turn the body and recover from the last punch.
Big movement can be misunderstood or trained poorly in ways that do not help in this development. It all depends on how it is done.