I don't see the problem with the SMN and BLM situation. In which way does it improve the game if the roles are switched so nobody wants SMN and everyone wants BLM? Realistically the only way to get this to work is if both do the exact same damage, with the exact same amount of skill.

In FF11 BLM > SMN was the norm. I played for a decade and had BLMs out-DPS me the entire time (and I wore the BiS gear). SMN strenght was stoneskin melee jobs or Alexander melee jobs, because DPS from SMN was the worst. Worse than that was probably that SE never buffed SMN. They added things like AOE auras with -20% damage penalty. Yea, the worst DD class surely needed lowering their DPS to raise everyone elses.

We don't want to shove SMN back into the "fine as solo, but sucks in parties" situation of FF11.