My experience is that, in the normal run of things, kiting causes more problems than it solves. In emergencies, though, kiting can make the difference between a partial wipe or a full one. For example, as a Bard, I've had a couple of situations in 4-man dungeons where something's gone wrong, the tank has gone down, and I've successfully kite-tanked a boss either long enough for the healer to res the tank or to finish the kill. I've also seen tanks using kiting when a healer has gone down to mitigate damage enough to allow the boss to be killed before they go down as well.