I disagree heavily. Blue Mage is not broken or a mistake in its current iteration. It enjoys the powers, like its instant death spells, because they didn't want to restrict it and be unfaithful to it as a job. In order to implement it in this game at all, that meant having to restrict it to be an expansion level tier behind.

If they made it into a regular job, they would take away everything that is enjoyable about it, and it would just be a generic caster, and it would likely lose spells that are favored entirely. I can understand why people want it to be a normal job, as it seems to be player/human nature to want to main a specific job that you have an affinity for, but sadly this is not the FF online for that. If you want to play an FF where BLU is king, you have options. FFV, FFVI, FFIX, and FFXI are all games where BLU was implemented and it is insanely powerful to the point of breaking the game if used with full knowledge. FFXI is even an MMO.

Also keep in mind that all of your arguments about BLU needing PF and other players and the hot moment is wrong, though perhaps true in the past. Now that it has Basic Instinct, a BLU with Basic Instinct active is effectively as powerful as 4 BLUs without it, only stymied by needing to constantly heal themselves. This lets BLU acquire 102 of the current 104 spells solo. While you can't finish your Blue Mage log that way, part of your argument undercuts itself by saying that the BLU content is a, "Why bother" or a "why bother more than once" kind of content. There isn't much gained other than completionism by doing the BLU log, so it's just something to get friends together for if you're bored with nothing better to do, anyway.

In its current form BLU is insanely fun. More fun to me than most of the battle content, due to its high power. I would never want to see it become a normal job, because it would lose this side of itself due to limited development time.

As far as the Masked Carnivale goes, in the modern era of FFXIV, the developers are afraid of corporate. They want to please a wider audience, and this means trying to make content that is both challenging but approachable. Which means that most content cannot be truly challenging, as the lower end players will be turned away if it is.

Because BLU is meant to be able to do everything, in order to be a faithful representation of its roots, it doesn't mesh well with most people. The majority of people who play FFXIV want no responsibility and no thought in their job class and play. They want to press maybe 5 buttons at most in a set order, and then turn their brains off. That is ultimately what you are asking them to turn BLU into, and that would be a travesty.