Let me preface by saying; yes I am aware that BLU can be brought into premade parties. Yes I know I'm not locked out of content. that being said locking BLU out of the Duty Finder/Roulette system is basically sending 1 Job back to the early 2.X days of Matchmaking.
Rather than the 49 grindable abilities we were given, I believe we could've kept the BLU identity intact with Monster skills learned via Job Quests just like with other Jobs. The Job Quests could've been "go search for Monster Skill X" you then get the skill at the end of the Quest. Thats the core of BLU (imo), learning the skills from monsters. Not the grind. Not the MASSIVE library (49 skills is more than any other game except maybe FFXI). The learning from Monsters.
People keep bringing up Bad Breath and Level 5 Death as examples as to why BLU would be a poor choice for group content, since it's either broken or underwhelming. Are we forgetting skils like Sleep, Repose, Tether, all the status skills from Ranged Phys DPS Role actions? most of these also don't work on bosses, but we still have them.
Lets look at a list of skills that would work as intended, or slightly modified to fit into FFXIV's gameplay. This is a list of skills JUST from FFV, so there are more skills to pull from.
Easily Translatable skills: Aqua Breath (Water Cone AoE), Flame Thrower (single-target Fire skill), Goblin Punch (Deals non-elemental dmg), Off-Guard (reduced defense), Vampire (non-elemental dmg and hp drain), Mighty Guard (Defensive Cooldown), 1000 Needles (1k dmg), White Wind (Heal based on current HP)
Tweakable skills: Time Slip (goes from debuff to haste buff), Moon Flute (increased party dmg at cost of mana like Foe's Requiem), Death Claw (Execute skill), Mind Blast (default BLU spell, or dmg that applies piercing/blunt debuff), Magic Hammer (dmg + magic vuln), Missile (Combo finisher)
I know it isn't as simple as I'm listing out here, I'm just pointing out that based off just 1 game alone, it's a very plausible idea to have developed a BLU within the same guidelines of the other Jobs. The dev team could easily take this concept I've presented and expand it into a properly built BLU that could then mesh with ALL of the game's content without fear of "the community" burning them at the stake.
Personally the idea of The Masked Carnivale sounds interesting, and I think the system they've presented is well thought out for it's given goal. It just doesn't seem to appeal to as many players as it could. It's side content, side content that with current information appears to have no connection to endgame level play or any indication that it will ever in the future. I feel that excluding BLU from this content does BLU fans and the potential of BLU the Job a disservice.