Well... Technically, there would be significant work in making it a full job, as it would have to be balanced alongside other jobs to make sure that it didn't do too much/too little DPS and didn't have any skills that were unusually powerful (Such as Peculiar Light being a far higher magical resistance down than any other ability, such as Contagion)
Though... Continually making new Masked Carnivale content would take up a lot of time, especially when they have to figure out what 1 skill you NEED in order to complete that particular round (Gosh... Carnivale has such a horrible implementation...) even if they could kind of just re-use existing enemies and just tune their damage/health and fit them in there...
Also, if they decide to make up any more BS rules for their weekly quests (Some of them are so dumb and completely contradict the entire ideology behind the Carnivale, which is to adapt your skill set to exploit enemy weaknesses, but then half the rules are "Only use X element abilities" or "Don't use more than 10 unique spells" so you're forced to just spam whatever it lets you use irregardless of weaknesses/resistances...)
But yeah... Making BLU a full time job is a frontloading of a TON of work, between creating new weapons from 1-70 (Soon 80), balance changes, progression changes (I.e. The fact that the optimal DPS rotation includes abilities from level 50 dungeons and EX Trials) as well as streamlining things so that you won't get people queuing up for dungeons with garbage spells equipped but instead get more easily directed towards a functional skill set (Both in terms of going and learning the skills and actually having a skill set up equipped that uses those reasonable skills)
But in the long run, it likely would end up having the less work required to expand on things, since it would largely do the same things that everyone else does, just with a bit more investment into spells to go and learn.