Seems like a hell of a lot of assumptions to make this a ‘no brainer’ precisely because of the things a scenario or formula can’t quantify, and those are momentum swings and psychological impact of failing.
How do you guarantee the other team won’t score? You have to assume in a game you are losing by two TD’s that at a minimum, the other team has shown it can score. And if it’s late? You basically do what you can to win; I’d like to see some numbers/probability on going for two after scoring your first TD in an away game where you’re favored by a single digit.
First, you should read through this thread as responses by Erial and myself will cover some of these.
On momentum, you are assuming this is a one way street - what if your team goes for 2 and misses, they will lose momentum. Well, what if they make it? Doesn't that give them more momentum? This impact cancels out. Also, if your team is down 2 TDs late in the game and you just drove to get one of them, does missing the 2 point really have that much impact to the team psyche? You still have a chance to tie the game with an 8 point play! Plenty of incentive.
You ask, what if the other team scores? Meaningless. If you had gone for the traditional extra point instead of going for 2 and the other team scores then it didn't matter if you went for 2 or 1. The parameters of this scenarios is that your team will be able to score 2 more TDs without the other team scoring, so a score by the other team is not even part of this scenario anyway.
What are the other assumptions? The math is really simple as I have shown. It shows an edge of 62.5% to win the game by going for 2 as opposed to a 50% chance by going for 1. Yes, the math is simplified on purpose so these numbers are not precise. However, 12.5% is an ENORMOUS statistical edge (this is what I think most people are missing). All factors discussed throughout this thread can make subtle differences to the percentages, but none are enough to overcome a 12.5% edge. None.
One last word. There were 2 NFL games last year where this strategy was successful and the team won. One was the GB Packers who made the playoffs by one game.