Ultimately in this current run of Dr. Who I suspect Moffet wants to solve the plot problem of the big picture - the Time War and how the Doctor solved it by tying up his home world and the Daleks in a logical contradiction.

I suppose the un-Doctor Doctor is the final incarnation of the Doctor and somehow is the one who decides to let everything be without his interference. That’s what I too away from his declaration that he didn’t have a choice, and he did it in the name of peace and sanity.

At least Moffet got a heavy-weight actor to play the final incarnation.