Since I started playing in BC a constant issue in pvp has been conflict in bg's between players of the same faction who are focused on objectives and those who are focused on maximizing kb's, damage and other stats. The problem with doing the latter is that it is essentially useless showboating if practiced exclusively for its own sake.
Blizzard has been quite unhelpful to those who believe in focusing on game objectives recently. The worst example of this was the introduction of censer of eternal agony. This basically formally legitimized all the kill-stealing and stat-maximizing players and gave them a specific metagame at odds with the basic premise of pvp.
More generally, there are a plethora of abilities which rely on kb's. The worst example perhaps is victory rush. Warriors have no other heal of note. They have to maximize kb's to survive. Even if you want to help the fc or whatever, without kb's your not going to be able to survive long without them. There are many others.
Further, there is a general desire expressed in the community for "balance" in pvp. Kill-based abilities make this impossible, and classes which tend to thrive on kb's tend to be unbalanced. Abilties which are kb-based tend to lead to fundamentally unbalanced pvp. If you get lots of kb's, you are over-powered, as kills beget more kills. If you don't then you are underpowered. This leads to fewer tight battles and more graveyard-camping massacres.
Blizzard could go a long way towards achieving balance by simply removing all such abilities from the game. Indeed, if they really want balance they could actually bring in disincentives to deliver kb's, since this would disadvantage the team that is already on top. But, of course, commercial logic being what it is, I doubt the player base would like it that much so they won't do it. Players aren't willing to nerf their own classes for the sake of game balance they (contradictorily) expect others to give up theirs.
What do you think? Is there some game-balancing advantage to these abilities I hadn't considered? Would you be prepared to see your abilities nerfed if i twas a unilateral cross-class move? Do you enjoy something about them for their own sake? Do you find them satisfying or whatever?