Playable Moogles, and why I think it would actually work

[Enkidoh]

It actually won't work, given the storyline and lore of FFXIV.

Here moogles are inhabitants of the Black Shroud only, and act as immediacies between the elementals and the 'spoken' races (that is, the playable races). They're naturally shy and don't normally like to appear to those they don't trust (in 1.0 after all, it was stated it was very rare to even see one, let alone communicate with one - to the point many used to think moogles didn't even exist).

After the Calamity Kan-E-Senna managed to convince the moogles to assist the city states with running the mail service (hence the Moogle Delivery Service). But that's really the limit of their interaction with others.

They also don't seem to be very mercenary - their culture appears to be very insular and mistrusting of outsiders, the exact opposite of the races of people who are naturally curious and industrious, hence adventuring makes an attractive career for hyur, miqo'te, roegadyn, lalafell and elezen, but for moogles... no.