There's a huge difference in Newton and Anderson. Yes, Anderson can make the throws. But what Newton brings is mobility and a running threat. With the running threat, the defense has to account for where Newton is at all times, or he'll take off for a ten yard gain. That generally means one less defender in deep coverage.
As for the mobility, look at all the plays that Newton extends with pocket awareness and his ability to escape the rush and then throw. If Anderson is back there, that's a sack. Frankly, Clausen's dink and dunk would be better than Anderson trying to be Cam. That's not to take away from him, but he just isn't physically equipped to do what Newton does.
I'm glad I read ahead because you pretty much summed it up. :thumbsup: