It would have been nice to learn a lot more about the lunarians in general. Maybe expand the lunar palace with a library wing like the ones that apear in FF5. Then players who are interested could learn a lot more, without it bogging down the narrative.

The fundamental problem is by exploring the lunarians more you are pulling them away from the sleeping mysterious race. Because the whole point was that at the end of the day earth was left to it's own devices. Having more lunarians wake up, or a bunch more cultural cross contamination kind of ruins the ending.