Who studies and why?

The Alexander Technique is a skill that be applied to activity in all walks of life. Though it is not a therapy as such it can be of therapeutic benefit (those suffering from joint disorders - bad backs*, necks etc., stress, RSI, breathing disorders and many other conditions have found the technique beneficial). *A study published in the British Medical Journal has shown that a course of Alexander technique lessons is highly effective in reducing back pain.
The technique has long been studied by performers (actors, musicians, dancers, singers) to develop fluid, natural movement through which true self-expression can flourish without stage fright.
Athletes also benefit from improved performance through application of the technique (for example, two of Great Britain's rowing coxless four team who won gold at The 2004 Olympic Games in Athens had been having Alexander lessons).
I firmly believe that the true place for the technique is with the young before they have developed strong habitual patterns that can harm health later in life.