Right, and hope for PI.
However, if you do it under normal circumstances, say in the middle of a game, your taking a shot. Most teams will do that once or twice a game.
If you're doing it at the end of a game and you're down by two scores... it no longer is an option... it's all you have to win the game. The playcalling and gameplanning is taken out of the equation and all you have is, "go deep and I'll throw it". It's the only option at that point. You're no longer taking a shot, trying to catch the other team napping... it's a desperation heave and the only way you have a chance to win the game. A game that has gotten way out of hand or you wouldn't be behind by two scores with less than 5 min. left.
If I'm a Commanders fan, I'd much rather have seen at least one long drive down the field against the Dallas defense, converting third down after third down to finally score on a one yard Portis run. That would give me confidence that my team could do that in future games. That play calling, execution and athletes made the difference. That my offense out played the opposing defense consistently in a crucial situation, drove down the field and won the game as time ran out.
Because there ain't no way the Commanders will consistently win games if they have to rely on making a lucky, 70 yard pass to pull out wins at the end.