I think that’s style. They want to show how rosey he spoke and lead the viewer to how his story has changed over time.
Considering the fact that the ad will (I hope!) run repeatedly and be seen many times by the same viewers, that’s probably a good way to go about it. The writer of the article is correct, I think, in the WHY of what makes the ad devastating. Obama has gone beyond failing to manage expectations — he’s lost control of them completetly, and the ad illustrates it using his own words.