A) Irrelevant.
B) Fine, I'll go through your original post point by point. I like to consider myself a pretty dang good Black Mage, not quite on Sfia's level, but enough to address this.
Edit: FORMATTING
Gear scales in this game. You will never hit the point of natural spellspeed where Fire 1 isn't required, as that requires a near 1.8 cast time on Fire 4 at all times, which is about 35% spell speed. Currently your highest natural gear you can get is 14%.
Every job suffers from mechanics, some just suffer a little more. Black Mage and Monk have the shortest, but Black Mage doesn't require a target or any other conditional to keep theirs. If a Monk has to run out of melee at a bad time, they're forced to either eat a hit (not ideal) or risk killing someone with said mechanic. Black Mage hits transpose. It's not a punishment to prevent the worst case scenario.
Swift cast, sharp cast, good use of Thunder procs. Transpose on the last boss if you have to.
Leylines is currently one of the only abilities in the game that actively changes your behavior. We need more of these, not less, as currently many abilities you simply spam on cooldown (Attack oriented ones) or mash during burst windows (Buff oriented ones). Leylines requires spatial forethought as well as minimizing the impact random aoes can have on it (Such as standing on the edge so the aoe doesn't cover the whole thing. Move to the other end. Easy street)
AF's timers and the conflict it has with the mechanics thrown at you is like, the main attraction when dealing with Black Mage. Loosening up this particular part of the Job makes it intrinsically less interesting. Easier, but less interesting. AF/UI timers aren't hard to keep so long as you keep your Spellspeed in mind and what it allows you to abuse. There is nothing more satisfying than skirting the timer.
Red Mage is also considered one of the least valuable jobs because you have fewer opportunities to excel. The Black Mage may not feel, at first handle, as good as a Red Mage in most content, but a Black Mage is one of the most satisfying jobs to optimize precisely because it's harder to handle. Split second proc management, knowing when you can be greedy, knowing when you can dump your leylines, knowing when you don't have to run out, abusing every timer you have.
That's the job. That's what makes it great. The simple rotation and mechanics are deceptive in this mastery because it's 'easy' to be okay at Black Mage, but very hard to be very good at it. If it's not for you, there's no shame in that.