I dislike nobling barbs as much as the next person, however, I can understand where it comes in handy. Indirectly hurting another person/tribe by taking away a readily available resource(s), as in their source of free resources, can have some impact. And if they want to target said nobled village? Well, if it's well defended than they will lose out in the in. I think we all can see the benefits of nobling barbs, but many of us(myself included) just love to have a conflict with other players/tribes. The interaction between players/tribes who are at war is far more appealing than the lack thereof that comes with nobling a barb.