Well why wouldn't they? If it's such an easy thing to do, why wouldn't you just go for the 2 to win the game, and not go to overtime? where the other team could get the ball first and get 2 first downs and kick a field goal.
It is not a good move to go for 2 when up by 7. You always kick the Extra point, to put the pressure on the other team to take the shot at a low percentage 2 pt conversion. Because then worse case scenario you go to overtime. If you go for 2 and miss, then the worst case scenario is the other team scores, goes for 2 and wins.
It just doesn't make much sense what you're saying.