If they put in beastmaster it would almost certainly be a "limited job." Which by and large, the commuinity doesn't really want.XIV is solid but they do not have Beastmaster still!!!!
"Limited Jobs" (BLU is the only one but they made a whole game system for it) have a lower level cap and are excluded from current content in order to allow them to be designed more freely without as many balance considerations (It doesn't have anything to do with "trolling" like some people think though.... People have said "If BLU could use the duty finder with everyone else they could troll by going into dungeons without any learned spells to troll people." But the reality is, you can troll on any job and there's no need to deliberately cripple yourself in order to do that....)
If the exclusion from current content was the only thing, I could live with that, but they haven't given BLU a PvP kit (which would be trivial to do) and are excluded from Deep Dungeons, despite the fact that they're tailor made to take on solo challenges, which is a dealbreaker to me.
BST would almost certainly get the same kind of treatment- they'd get something special like a monster collection mechanic, but the diverse range of monsters and the skills they grant, much like BLU, would make balance difficult and thus they'd have to be a Limited Job. No thanks.