I don't understand the BLU hate.

It's always been a very gimmicky busted job in the RPG versions, which doesn't really fit in an mmo setting. The class was completely busted in XI and they never got around to toning it down. It a strict trinity setting of Tank/Healer/DPS, blue mage doesn't really fit in, in my opinion. It's never going to be the odd, busted and wonky mage you want it to be from old FF titles, at least not running "real" content.

No matter how the class was implemented it was going to make a certain number of people unhappy.