I skimmed the entire thread, and was shocked no one brought up this point:

Quote Originally Posted by YoshiP, paraphrased
Imagine you go to fight Omega M/F. The battle starts, BLU casts Level 5 Death, and it's all over! Obviously, we can't NOT give BLU Level 5 Death, or nerf it against bosses, or the job wouldn't feel like BLU! So, overworld only for you guys!
So, BLU is going to get Level 5 Death, it won't be nerfed, and can be used in the Overworld? That's gonna make Hunts mighty interesting... XD

Having said that, here's my thoughts on Blue Mage as revealed at Fan Festa...

I'm pretty deeply disappointed. I'll play their Blue Mage minigame, and likely enjoy it, but it's frustrating to realize that the devs and YoshiP lack the imagination to make Blue Mage a real, viable job in this game. Folks in this thread have pointed out that Blue Mage as we received it corresponds neatly with comments YoshiP made on the job four years ago, and why HE felt it could not be made to fit in a MMO. The truth is, fans of BLU have been hoping that these past four years would have been time enough for YoshiP to pull his head out of his ass and realize that his vision for BLU is not the only possibility!

YoshiP said himself that everywhere he goes, folks ask for Blue Mage. When is it coming? This alone makes it clear that Blue Mage is a highly desired job. Rather than throwing something together just to make them shut up, he should have found a way to make it WORK. NO player who asked for Blue Mage wanted what we were given. None. Some may be okay with it, and some might actually be enthusiastic about it - but when they asked, they wanted a job that could stand shoulder-to-shoulder with other jobs in this game. They wanted Blue Mage to be their main job, with which they tackled all of the game's content that interested them.

When a job's concept does not perfectly align with the game's design, you alter the concept to fit. This has already been done with MANY jobs in this game - SMN as a DoT specialist with only three summons, Dark Knight as a tank without and form of self-harm, Bard as an archer with only a handful of musical buffs - all of these are pretty significant departures from the jobs as we've known them in other Final Fantasy games. And yes, some players were disappointed with these changes. Blue Mage should have been no different; there are many, many ways it could fit into the game while still being recognizable as a Blue Mage - and yes, the changes needed would have alienated SOME fans of Blue Mage with very particular ideas about the job. For the majority, however, they would understand why the changes were necessary, and accept them.

The concern that parties wouldn't accept BLUs without certain spells is a crock as well. It's no different than parties refusing jobs that haven't learned all of their job abilities. Do you want a Warrior in your party who does not have Deliverance? A Black Mage who does not know Fire IV? A Scholar whose only curative abilities are Physick and Adloquiem? All of these are possible by avoiding job quests, and no content bars a player who has not completed them! Blue Mages who do not learn important spells will be kicked from parties, it is true - and that is PERFECTLY FINE. Just make those important Blue Magic spells as easy to acquire as other jobs' abilities are, and no one can reasonably complain.

Blue Mage doesn't need to have a bazillion spells from which they "equip" a certain number. The only time in Final Fantasy that BLU has been done this way was in FFXI. Therefore, the argument that it would be too difficult to balance so many spells is moot; as long as the number of Blue Mage spells is less than or equal to the number of abilities other jobs get, they should be no more difficult to balance. The argument that some iconic Blue Magic would be useless in a lot of content (like, for example, no boss would be susceptible to Bad Breath) is also not a good argument, as many jobs have crowd control abilities in spite of the fact that, outside of a few specific mechanics, they are useless in such content (Black Mage's Sleep, for instance, or the Role Action Foot Graze).

There have been many discussion threads over the years talking about Blue Mage and how it could work. A lot of good ideas were put forth, as well as a lot of terrible ideas - but good or bad, it's not hard to see that there's more than one way to look at Blue Mage. It sucks that YoshiP was never able to see that.

Long-winded rant aside, I do have to say that I LOVE the look they chose for Blue Mage. It's very reminiscent of the Final Fantasy V look for the job, and I love the "masquerade" vibe. The use of a cane as a weapon is a classy touch, as well.