So, adding into the many Blue Mage threads on the forum already, I wanted to state my own opinions.
With Blue Mage being a "Limited Job" it's like a beta job. Perhaps as SE watches how the preformed parties utilize blue mage they could collect the data, analyze it, and ultimately turn it into a full fledged job.
Basically seeing what abilities work well in a premade group setting versus those that don't and how it could one day not be a "limited job." I view it as a very good support job as well.