Hang on, I’m not sure why you think a magicite/esper has no relevance on the overall story or setting of VI, which is the contention of /u/Chaos-B.

Let me put it to you this way - if a character dies, does that mean his or her previous actions, motivations or impact on a story is null and void? In this way, if you consider an esper turning into a magicite as ‘death’ or ‘suspension’, isn’t this the same as a character dying?

In this way, I would agree with Chaos-B that the ‘esper’ or ‘magicite’ or ‘Guardian Force’ or ‘aeon’ concept is probably so core and integral to VI’s story and setting that it should be included with X and IX (and XV to a lesser extent).