You are basing all of your opinions on hypotheticals, which are great, but rarely work out, especially when you add more of them together. A lot would have changed had the fake punt worked. The game was still close at the time so the final score is irrelevant at that point. It's one thing to say statistical probability drops only a few percentage points after a single play, but there are endless other variables that enter the mix. That pass play to Dez very well would have been a different play had they punted and the defense would have likely be in a different defense that far away from the end zone. If they had punted, what if the Cowboys return guy muffed the catch and lost the ball? What if he caught it and on the first play, Murray fumbled? There are so many variables to consider that trying to use what-if's is a pointless argument.
The bottom line is they took a huge risk, it back fired and and took a close game and threw it away. If the Cowboys had thrown the ball to the gunner and it failed, most of the people griping right now would have been complaining how stupid Garrett was to attempt that on the Cowboys end of the field. I can tell you even if it worked, I would have thought less of Garrett for doing it. While I detest his conservative play calling, especially over the 7 losses in a row, trying to be non-conservative at point like that would have been twice as foolish.