I feel like this would make red mage just another ninja. If red mage was turned into what the OP did, I'd much rather just play ninja and avoid having to toggle a stance every time I wanted to switch between casting and attacking.

People need to understand that the red mage was always the jack of all trades, and the only two times the red mage was a master of anything was debuffs in FINAL FANTASY XI and arcane magicks in FINAL FANTASY XII: The Zodiac Age. In this game, it's a Disciple of Magic DPS with Vercure, Verraise and weaponskills, things no other Disciple of Magic DPS can rationally boast beyond summoner's Resurrection (which basically requires Swiftcast).

Also, Dualcast is part of the red mage's history more than any other job. It was sometimes called Double or Doublecast.

Finally, it's important to point out that this job has always been the red mage. Of course magic is going to be at the forefront of what this job does. The OP is trying to change that, and I think that demonstrates a lack of understanding of the job.