The Blue Mage is being added in patch 4.5 for everyone who owns the game.
The drawback is that the job is designed for solo play and can't be used in any duty finder or end game content.
That's the short version.
Edit: I wrote this because I skimmed your post before heading out the door to run an errand, and assumed that you simply hadn't heard, rather than you don't understand that people dislike the entire concept of a soloist-only job that's locked out of doing relevant content with other jobs.
No one is complaining about the carnivale itself or the unique blue mage leveling system. Though I personally wish the carnivale was designed for more than just one job.
