While I don't think there is anything inherently wrong with a story-mode version of coil, it seems kind of goofy to spend developmental time on something that will have no replay value. I guess they could add it to duty trials, i really don't know. As far as using it to practice for the more challenging version, I don't feel that story-mode versions really prepare you for their harder counter-part honestly. Ramuh HM, for instance, doesn't really even come close to even preparing you for ex mode outside of giving you a general idea of what can happen.