Well, I would never say that it destroyed the whole movie, but Lucas's reasoning behind it does compromise the whole redemption aspect. Besides, that line of reasoning is the best possible motive behind it. But I have my suspicions that:

a. It was simply done as a futile and half-hearted attempt to connect the two trilogies together
b. It was done to make fans feel completely obligated to watch the movies in their improper order of I-VI. In other words, a laughing, "Screw you!" to the fans.