So lore and some binary are the only things making them unplayable.

Running counter to the above reasons, Moogles are popular and very integral to FF as a whole. Ask a dozen people for their favorite character from FFVI, four of 'em gonna say "Mog!"

As for lore making it unreasonable to introduce a new playable race, that begs the question how they'd be managing anything they introduce. Some folks want Bangaa, I am not among them, but there it is. Others want Viera. In what lore were Viera ever mentioned? Never. Dev Team gonna change things and make it up as they go, fitting the lore to the race. The same could be done for moogles.

Plus, it's the end of the world. All bets are off!