Dozu, I think your tennis knowledge is too low to write posts like above. You play a recreational tennis. Your technique is recreational. Your understanding of tennis is recreational. And you think that what works for you, at your recreational level, should be copied by everyone.
Your analysis is naive and completly wrong. You perform much better when you insult people.
All I can say is that my backswing is a result of careful physical and biomechanical analysis. And yes, you are right, many pros do larger backswing. But you don't know, why, and I do not want to explain.
Also, I do not use one type of backswing.
You really think that the difference is so huge? Especially if you remember that Federer hits lower ball and adds more spin?
What's the function of backswing? Physically, biomechanically - why do we do backswings?