Isn't that just taking it from one extreme to the other? I agree that wars to the death shouldn't be the norm, but to disallow them completely isn't the solution IMHO. Some situations do warrant total destruction of either party. And unless I'm missing something, this idea would only make giant realms even more powerful, since a realm with fewer regions will suffer far more from losing 1-2 than a realm that has 20+ regions to start with.
