As one who was disappointed that BLU got the solo announcement, I am warming up to the compromise of premades. Premades, people can consent the state of the blue mage in their party, in duty finder they cannot beyond a kick, which could mess up the duty finder eco system, either in a BLU that cannot function well or just having to kick a BLU and get another DPS in. There is also the fact Blue Mage is not restricted to a role and the system is not built around being able to select a role to queue as like in WoW and I suspect there would be core system changes needed to get it to work like that. Whilst there are solutions to each problem, it does seem like something that can create a lot of problems. There was going to be compromise somewhere regardless and they've had to find where to make that compromise and thusly you have a situation where there's going to be people not happy regardless of what it is.
As they've implied BLU is the "first" of its kind, this suggestes they want to play with this idea further in the future on other jobs. One complaint has been that they keep dishing out the same formula, so it may be a good thing they're trying something new/different. And for comparison SMN was a disappointment on release, whilst there are many of us who love SMN, they did sacrifice its identity to get it to work within FFXIV's system and some people are still unhappy about and they're currently caught between two identities, a DoT mage with a pet and something that summons powerful aetheric beings to fight for them. This system may well in future give people the summoner people hoped for in addition to the summoner we got. Because it is still a Final Fantasy title, so people do have certain expectations about how certain jobs should be. And a job's identity is difficult to capture when the system don't give much leeway. Red Mage I think they were clever with, because they were able to keep its identity, despite Red Mage being a jack of all trades job.