I agree with V, especially in BG.
Killing the opposing faction is the most fun part of BG.
Of course winning is a prime objective, but the mass battle is what provides the fun. 

The only point I want to emphasize is in BG it is most fun.
Outside of BG I still do not see a point in using my high level characters to gank low level characters.

To me, no fun killing something my VW can one shot, and that slows me down from questing.