While the early returns for Cam do the same, it's still VERY early and his game logs trouble me. If the Panthers continue to operate with Cam as only a secondary option at the goal line instead of the primary option (as they HAVE been doing over the last 6 games), then suddenly Cam loses a TON of value. He simply isn't going to continue to consistently produce 10+ yard rushing touchdowns at the rate that would be necessary to maintain the value some are assigning (based on the assumption that he would be the goal line back).
I don't necessarily disagree with your overall point here, but I think you need to account for the fact that exceptional players are going to do exceptional things. The reason Calvin Johnson has been getting so many receiving TDs compared to other #1 WRs is because he offers a rare skill set and combination of height/speed/strength/skill that's unmatched by any other pro wideout. Why can't Cam do the same thing at the QB position? Why can't he keep running for TDs? I've never seen a QB with a better combination of size, speed, and passing skills. Cam is exceptional, so I expect him to do exceptional things.
This suddenly places a huge emphasis on the need to improve his passing production to achieve that value. I think he is a great player and absolutely could reach the passing production necessary, but I also acknowledge there is a very real possibility he won't (he has looked both great and terrible in the passing game at points this season). When there are so many other very young, very proven, very talented players that are options at 1.01, why would you want to take the giant risk that either Cam Newton's passing production will increase substantially or the Panthers will revert back to using him as the primary option at the goal line? Additionally, why would you want to take that risk when even if everything goes right and it happens like you wanted, the likely result is the production level that Aaron Rodgers already provides with essentially no risk assigned at all?
First off, I don't see that many great options at 1.01. Some of the super elite players like Larry Fitzgerald, Chris Johnson, and Adrian Peterson are reaching a point in their careers when their age and mileage are beginning to affect their outlook and their trade value. Players like LeSean McCoy and Ray Rice are putting up great numbers, but if you ask me they're examples of "right player, right situation." I know I'm probably in the minority here, but I don't see either as a super elite Peterson/Tomlinson/Faulk type of back that you can build a perennial dynasty around. That leaves a pretty small group of names who offer the same kind of short-term/long-term value combination as Cam:Aaron Rodgers
Calvin Johnson
Who else? Maybe I'd chuck Trent Richardson, AJ Green, or Dez Bryant in there, but none of those guys are any more proven than Cam is.
I've already said that I think Cam stands a good chance to improve as a passer. He ranks 19th in the NFL in passing TDs, behind such luminaries as Alex Smith, Andy Dalton, Colt McCoy, Mark Sanchez, and Ryan Fitzpatrick. I think his numbers will improve in this department and while some of that might come at the expense of his rushing, the overall upside is still very enticing when you consider what he might be capable of when he eventually has the kind of career year that Manning, Brady, and Rodgers eventually had with their respective skill sets. What is he capable of if everything clicks for him? 30 passing TDs and 15 rushing TDs? I think his ceiling is enormous.