I was thinking maybe the job quest consisting of us using a strange allagan relic to collect DNA from "unique" monsters that allows us to shapeshift into those monsters with it. Not a collector type of job as I think that would get it stuck in a limited job section which I think would be better suited for Beast Master and BLU. I'm thinking more of a multi-role job that has a role determined by form and forms are gathered from job quests. As for the forms aesthetics I'm on the fence of half-humanoid forms and full transformations as both are pretty cool in their own way.

I kinda disagree about beastmaster becoming moot due to the feel of having a monster as your companion is very different from being able to take the form of a monster yourself.