To date nobody has been able to design an acceptable CVT for bike use. The attempts have all been either mechanical failures or unacceptably heavy and inefficient. So it's not a "more feasible solution", at least not so far.

The pie-in-the-sky electronic shifting system proposed by the OP may indeed be possible some day but current prototype electric shifting systems by Shimano and Campy (and Mavic's two failed commercial attempts) are just electrically shifted versions of current derailleur systems. They replace the shift lever, cable and hosing with servo motors and a battery. The only advantage I can see is you can install the shift buttons anywhere and have them in more than one location.