@Gregory Diamond : First of all, I agree with all your Physics reasoning, which is very sound. You are also, definitely, a very good player. But I think you are underestimating the stability you can get with a single handed forehand. Having the arm close to the body while making the forward swing and contacting the ball in front of the body as the pros do, puts the whole body behind the ball and arm, and minimizes racket recoil. The arm is positioned such that, like a trap door, it can be moved one way easily (forward) but there is strong resistance to movement the other way (backward), thus solving the problem of control. And you get a few more degrees of freedom in arm movement with a single hand which can be used to create more pace and spin. If this were not true, in the competitive and potentially lucrative world of ATP tennis, a lot of people would have already started using what you are prescribing.
This is not all my original thought, I confess - I discussed this with a friend of mine who has a very high level performance coach, whom he consulted.
But let us agree in advance to disagree, since we want to avoid infinite loops!