Big Bridge/Big Keep aren't really good examples of when to not cleanse debuffs here, since Esuna/Leeches does nothing for them.
Big Bridge's confusion is cured by healing the target to full.
Big Keep's mini is cured by having the tethered pair run into each other.

I actually can't think of any fight where a debuff that can be Esuna'd/Leeched shouldn't be cured for any reason.