Except the rule is that a Time Lord gets only 13 lives without getting a new regeneration cycle, and "The Time of the Doctor" accounted for all 13 -- Hartnell, Troughton, Pertwee, T. Baker, Davison, C. Baker, McCoy, McGann, Hurt, Eccleston, Tennant 1, Tennant 2, Smith. And getting a new regeneration cycle is supposed to be exceedingly rare and exceptional, a gift from the Time Lords that the Doctor never expected to get. If this was the second time he got a new regeneration cycle, that totally undermines its importance. I don't understand why anyone would want that.