You see, that's where I think the comparison is not fair. The problem with Limited jobs is not that they are limited, it is that they are jobs. So in that sense (and with the Final Fantasy history), people potentially expect any job to join the list on FFXIV's take on jobs, at one point or another.
Calling BLU a "job" crosses it out of the traditional jobs. And that's why people are angry I think; not because it is niche content.
I imagine that if they had made BLU a Gold Saucer glorified minigame with the Carnivale and all, people would possibly accept it as it is and still imagine a proper BLU job would come out some day.
Now based on what is actually in the game, I'll see with BLU 60 and what it brings to BLU itself. If it does not solve the problems I have with BLU, then I'll just wish the devs can keep current BLU but add a real BLU to the casters, with fixed spells and rotation. The devs would "just" have to state that we should not expect any "solo niche content" for any other job. But that's still a lot of resources.