Main reason why i think it isn't used that much is because in the wild you can gain rune, in CWA you can't. In CWA it isn't as thrilling, losing a rune set, not being able to gain it back, and simply walking to to bh and back and fight again. In the wild, there is that extra thrill. It's hard to explain but the crashing threat and other clans watching/ac'ing fights makes it a lot more interesting than dangerous CWA.