Debuffs Need Multiple Categories
One thing I feel is missing in terms of design space is the idea that buffs only have two categories, curable and incurable.
In various RPGs buffs usually come in multiple categories like disease, poison, curses, etc.
If debuffs has multiple categories, you could also create additional design space and give different jobs different cleanses.
BLM could have a remove curse.
MNK could self-cure poison.
WHM could AoE-heal diseases.
If you split the debuffs you widen the design space. Healers should still be the best at it with multi-cures and AoE type-specific cures, but it allows options in terms of what gets what. Also, if the cures are split that adds some additional thought to jobs with multiple cleanse types.