I agree, I've every spell save doom and done a fair bit of the carnival and will finish it up soon. I'm fine with the idea of limited jobs, but it need to earn that limitation, it need to feel like "Yeah, this really wouldn't work in current content." BLU only feels that way in a sense of being pretty weak save fore trash killing.
If not just BLU but limited jobs in general are going to work, they need to feel all powerful in the content their allowed to do, if their limited to old and outdated content then they need to do it better that a max level normal job, let them two shot bosses, solo coil, run around and feel mighty and do interesting things.
In the ocean that is FFXIV if some jobs are going to be asked to sit alone in their own little ponds, they need to be the biggest baddest fish in said ponds, they shouldn't have to keep asking the sea fish to jump into their ponds to help them, that defeats the point.