They theoretically weren't killed. Just sapped of their powers and made useless. Just like the espers. You do have a very good point. Good job on taking the analogy deeper then I was thinking. There were 2 magical creatures. The espers and whatever the hell the warring triad was. The espers created Terra and all the mages of Thamasa. The espers source of magic was the warring triad, who had no source of magic other then themselves (Gods have no source of power, which is why kefka was not a god.) When Kefka sapped the power out of the warring triad and was killed, the espers and Terra's and Thamasa's mages powers were gone. The espers life force is magic, so when you take it away, they die. When the ultimate source of magic that as no source it taken away, you lose all magic, never to be recovered again. Going deeper on the analogy, if you take away everything that supplies electricity(yes, that would include lightning), How are you going to power the heater even if you get another one?