Why do people want Blue Mage in this game?

[Tanathya]

There's really no "proper". Each job has seen changes in each FF game.

But everything followed a pattern, all of them have signature traits. SMN has always been about the summons, summons weren't just a minor sidekick like they are here, for example. Not even gonna mention DRK, already did many times and I'm sure there'll be more to come. BLM's signature spells were those three, yes, but they took away what made a BLM in the first place; elemental weaknesses.

The playstyle itself isn't bad. However labeling it as something it is not is completely pathetic.

This exactly here.