The problem with all of this, despite your suggestions being good
All well thought out suggestions, and I salute you for them.
They have two specific problems.
1: That's not blue mage. That isn't 'fixing' blue mage as some would say, that's 'completely replacing it and giving the new thing the same name.' What you have described is an entirely new job, and not one SE wants, which brings us to point 2.
2: SE doesn't *want* blue mage to be a normal job. They want it to be a limited job, and no matter how wonderful, intricate, well thought out and intelligent the ideas for making it a normal job-which yours are, by the way-the devs don't want it to be a normal job. They want it to be side content, to be something for players to do outside of normal content, something to say 'I'm caught up on MSQ, now what do I do, I can do this while I wait for more content', and that, in essence is what BLU's purpose is in 14, just like relics. Something to keep us busy that is not directly tied to the main story, to give them time to work on it. No matter how brilliant the idea to change it to a normal job may be, doing so would defeat the primary purpose of the job and that is, side content to keep us busy.