The Moogles are an oddity because unlike the other two tribes in Heavensward, they were not created for the expansion, they existed as far back as 1.0, and minions of them (Vanilla from the CE and the 2 Merchandise ones) also existed at this point. They are also unique as there is no conflict with other moogles, as in there is no tribal infighting. As such there is no need for a 2nd set of Moogles and thus no need for a 2nd minion.

The Dragons on the other hand already have 3, but the other common thread for the BT minions is that they are clockwork replicas, mammots. Which Midgardsomnr is not, and Banamut is no longer available.

My guess is that we will return to the 2 minion per beast tribe formula unless the new tribes inclue the Qiqirn (one crafted minion, so a similar case to the Moogles), or the Goblins (which have 2 minions already, including a crafted one. so, no minions?) Mamool Ja are the only existing Beastmen/non-spoken not to have minions.