The issue with creating short decisive battles is 99.9% of the players won't be able to take part as it will be over before you get there.
While that's believable in a real world sense and progresses the game in a single player game it makes for poor multiplayer.
War zones are the equivalent of PvP arenas, if you are playing in open you might find other players dropping in and joining on one of the sides especially in areas of high interest.
The battles could last minutes or hour depending on the participation. You can always respawn a new battle somewhere else in the system, similar to the typical PvP match - eb and flow of conflict and all that. The conflict can persist even if the battles do not.