In 20 years, I expect most movie actors and actresses will be computer generated.
From what I understand the difficulty in computer-generated characters is with getting TOO close to reality without being real.
Apparently, so long as we can tell the image is not real, we have no problem with the inconsistancies and unnatural aspects. But at some point, the images get a bit too close to reality. The conscious mind begins to lose the ability to distinguish it from real, but your mind still can tell — and it gets upset.
So for now, those using the fake actors are purposely making them less real. In my opinion a few of the commercials have gone a little too far, because most people I ask about them say they feel a little “odd” after watching them.