I don't know about anyone else, but I never see other NA BLU using anything except physical spells. I think JPs are probably also called on to use things like Temporal Shift for elemental stun or Blank Gaze for light-based dispel, and against NMs you want to have as much Mag. Acc. as possible since abyssea NMs tend to have increasing resistances.

For people using BLU as a pure DD job, this would not be an issue.

Also, the Macc. swords contribute to Sanguine Blade accuracy and have a lot of MP. Both of those are also contributing factors. Heck, for all we know they could be blinking in Str swords after the first 150 MP is used.