So before I get into this I just want to say I originally got the BLU info from a friend but have read up on it a bit.

From the way BLU was explained to me it mainly sounds like its just a time filler, kinda like Gold Saucer or POTD, HOH just with less incentive. To me it just kind of sounds like Square is either running out of ideas and they just were like "Hey people want blue mage so let's give them blue mage." either that or their waiting until the expansion to release a lot of new content, like expanding the Saucer. Personally I very much hope it's the latter.