I could buy that theory other than the fact it's already been done once and seems unnecessary by your own reasoning, unless the Daleks take advantage of the regeneration recovery time to kill everyone..
Completely agree. If the finale went this route then this is, in a way, no different than the events in "Turn Left". Been there, done that. Plus, even the whole "rewriting history" thing has been done before, by Rose, which I might add was in a season finale involving the Daleks, so once again, "been there, done that".