Fire II is really bad.
It's so bad that spamming Freeze and maintaining Thunder II is better at Levels 35-49. I don't mean that it's more convenient (though it is), I mean that it does significantly more damage.
I don't even want to tell new Black Mages at this level range that Freeze spam is better, because it confuses them at Level 50+ and it upsets them that such an "oversight" could be possible.
It used to be 170 potency at the end of ARR, 100 in Heavensward, 80 in Stormblood, and has been totally unusable at levelcap ever since.
At least buff it so Freeze spam isn't ever optimal.