Blue mage at patch 4.5

[Fyce]

3 jobs would have been better, but that's OK. Let's settle for less when we could have had more!

The BLU they introduced doesn't need anyway near the same amount of balance regular jobs do. It uses already existing animations/skills. Being limited to Lv.50 drastically reduce the concerns about how this job would play in up-to-date content. Therefore, the amount of work needed to make BLU as it is now is very likely much less than trying to shoehorn it into the usual mould. This means that there's absolutly no evidence to say that we could've had BLU as a third "regular job" if it wasn't made the way it is today. Besides, implying that getting only 2 jobs instead of 3 is "getting less" is completly putting aside all the content provided for BLU. We are not getting less content. We are getting different content.

The ONLY identity for blue mage that's been consistent is that it learns abilities from monsters, then uses them on their own. They have never had a full carnival sidestory, and they've never been excluded from participating in the game itself. You can bring Quistis or Quina or Kimarhi with you the whole game.

That is an incomplete description of what a Blue Mage is about, and doesn't take into account all of the very weird and situational skills they could use.
Aqua Breath is useful on enemies weak to water. That's why you learned that skill, and why you'd choose to use it. Making it a skill that "deals magic damage" -like every other magic spell in this game ultimatly is (Aka. "Fire" doesn't deal "Fire" damage)- would completly defeat the point of the BLU having an arsenal of situational skills that you have to use correctly.

It would likely take less work to do that than to do the Carnivale and balancing that. The difference is BLU in relevant content is a better long-term option than being relegated to content that'll last, at most, about 6 months (and only because people will be bored as hell with nothing new coming after 4.5.)

See the first paragraph regarding "balance".
As for the content limited in time, FFXIV is absolutly full of it. There's a metric ton of content that people aren't doing today, but that was fun to do when it came out. Besides, they said that they would increase BLU level cap with time, meaning that new content would be regularly added for it. Saying "it'll only last 6 month" out of the blue without any argument/evidence to prove that claim holds no ground.