Personally I like the idea of VoV; I just think that there should be some expenses associated to it. Many, many times it does not matter if you lose your unit (or 99% of its strenght) if you just manage to keep the territory. If using VoV is 'free' then there is no reason for an exploiting player to use it all the time to keep what he has gained by gamey tactics. Paratroopers fighting to death come to mind, as do troops which have landed and taken strategic targets like Leningrad, and who by fighting to death keep the territory until relieved. I really do not believe that attacking forces (even when momentarily on defence) would fight to the last man.
One solution to VoV would be to allow it's use only on owned core provinces, but even that would not solve the problems that can arise when your border to enemy is 10 provinces wide with 10 divs in each. You concentrate your forces so that there is 1 div in 9 provinces and the rest in the breakthrough province, who advance while the rest 9 fight to the death...:wacko: