The thing is it needs an overhaul for it to be different from the other casters if it were to be regular job. It can't just be spamming 1-2 filler spells while weaving plethora of OGCDs in between. BLM is the sustainable DPS without any specific burst phase, RDM have a buid up to one burst phase, and SMN is going back and forth through 3 different burst phases. What kind of combat mechanic would BLU have were it'd be a regular job? Not only that, but the devs also have to make it balanced with the other DPSes.
The concept of learning spells from monsters is of course already unique to BLU, but we're talking specifically about combat rotation here.