I think what you have here is akin to the massive errors in polling we see in elections.
The clear reveled preference of the consumer they did not like New Coke, they expressed this by not buy it.
Limited market research will often give the company the answer they are already looking for, there are plenty of examples of this
Further is completely self defeating to New Coke was better than Classic because Coke Zero failed. First off, Coke Zero tastes NOTHING like Classic, To me aspartame is actively bitter to me not sweet. So Diet Coke or Coke Zero or any other drink with aspartame in it is a no go.
But aside from my personal tastes, Diet Coke has the first move advantage for the zero cal beverage, so all of your arguments as to why classic won over coke would apply equally well to why diet won over zero.
Further still, I think there is a massive consumer disparity between the consumers of zero cal soda, and people that want regular soda. Comparing their consumer preferences is going to be very hard