Noseband too tight?

This week's Brain or Pain newsletter included a comment about nosebands being too tight on so many horses, and how this could potentially affect performance. Can you imagine the professionals on Strictly Come Dancing being able to move so freely if they had their jaws clamped shut? There is a direct link between tension in the muscles that close the jaw, and tension throughout the rest of the body. A tense muscle cannot extend to the end of its range of movement, and since in horse competition range of movement is a factor in performance, this causes reduced performance (think of how restricted your movement is when your muscles are tight and sore the day after you've exercised too hard, as an example). A jumping horse needs to be able to stretch over the fence, a racehorse needs to be able to stretch his stride to gallop faster, the dressage horse needs to be able to extend his forelegs, the hacking horse needs to be able to move freely up and down hill, and that's just the beginning.
This comment has brought several responses, all agreeing with me that strapping a horses mouth shut to hide unwanted behaviour is not the right thing to do. There aren't necessarily any other easy answers, but as responsible horse owners, for the sake of our horses comfort, we should do our best to identify the cause rather than ignore it.