Given the above, I don't think removing positionals would make the those jobs "boring" because:
1) Hard fights are mechanic heavy and either make it nearly impossible to maintain full uptime + positionals anyway OR remove the need for them entirely given the nature of the boss.
2) You don't even effectively use them half the time when soloing.
3) They are removed from content where it doesn't even matter anyway.
The benefit of having them is:
1) Making a job slightly harder / more in-depth to play.
2) Allowing a distinction between bad, good, great players (which I think they were trying to get away from anyway, thus the changes)
1. It's supposed to be impossible at times, otherwise what's the point of positionals? It's so really good players can have a means to perform at a job better than someone else when available.
2. Half the time is ok, as long as not never.
3. No comment
4. This combat system is bare bones as is, I like depth when applicable.
5. The changes to Monk are so it is not as bad a disparity. Otherwise they would have removed them completely.
You could make this argument in other areas as well.
1. Why does X job have better AoE?
2. Why does X job have a good self cure and my job does not, I like soloing too?
3. Why does Warrior have to aim Overpower and Dark does not have to aim Unleash?
When you break it down this is really a dislike because X job has to do it to be great while Y job does not. If that is the real argument then maybe they could devise a system where every job can and should take advantage of positionals instead of just some?
How about a global system that can add depth to all jobs depending on situations. Passives that are accounted for depending on positions and circumstances. Certain offline Final Fantasies have these. I will say take a page from XIII for this game. But pseudo fit it to fit the theme of this game. I will list the skill then why it makes you want to play better for bonuses below each skill.
Passives depending on circumstance:
Blindside- Deals critical damage with any damage skill executed from behind.
Encourages all jobs to execute damage skills from behind.
Pincer Attack- All damage skills executed from sides lower resistance to your specified weapon/magic type for 12 seconds.
Encourages all jobs to execute damage skills from the side.
Vigor- Boost damage of auto attacks when your HP is high, effect diminishes as your HP lowers.
Damage uptick remains higher when you avoid damage.
Chain Attack- Increases Limit Break accrual when multiple players target the same enemy.
This one rewards you for targeting the same focused enemy when multiple enemies exist.
Faultsiphon- Slightly charge TP/MP gauge when attacking a target with status ailments.
Encourages you to hit specific enemies with status ailments to manage resources better.
Lifesiphon- Restores 200 HP upon dealing the killing blow to an enemy.
Encourages you to finish an enemy almost dead first.
Deathblow- Kills any normal enemy in one blow if attacked with a skill while stunned.
Encourages you to take advantage of stunned enemies.
Brittle- Player is inflicted with a severe defense down penalty when attacked by 5 or more enemies at once.
Encourage you to fight groups of enemies and not zones of enemies, could allow for harder hitting/dangerous standard enemies.
Those are some, could get really fancy especially if a stagger system was a thing but not going to go into detail because this is just a thought and none likely to happen. If I had my wish combos and selfish rotations would be pruned down replaced with less skills but more party synergy or taking advantage of situations, perhaps a skill chain system, aka comboing skills with yourself or others in no particular order but the depth is the combinations/variations you do.