AFAIK lens polishing using a pitch lap is capable of holding or adjusting curvature to approx 1/4 wavelength of light. I do not believe that a CNC generated profile would come close to that although possibly the highest quality machine (read highest cost) might come close. Having ground and tested a telescope mirror; I still marvel at the close tolerances obtained by a hand process. There is a very good reason that lenses are made the way they are.