I've thought the same question. If the overall game is about having the most capture points at the end of war, then its also about limiting the other clans to score less then you. So you have to decide what is the better idea, going out and continually trying to capture the points, or defending your own.
I'm not 100% on this next bit but I think i'm correct in saying that the capture points you get from each node decreases by 1 each time someone captures it (10,9,8 etc, you get it). So if you defend one for the whole war, there is some big points that no other clan has collected.
So i think the winners of the war will be the clans that can effectively attack and defend their objectives.
Hope this helps.