If you go down 2 scores, which is what happened with a failed 2 pt converson, then as we saw you have to attempt an onside kick, which has been successful only about 10% of the time. Make the extra point and you only have to stop Atlanta once, and you don't need the onside kick, as you'd have time to score a td, though of course you would still have to get the 2 pts after that score.
Really either way it's desperation time, it worked out so I'm not sure what all the debate is about, doesn't really matter....