I hadnt even noticed that healers arent doing this. Besides slow and pacify I dont much care wether its removed or not. Disease is useful to remove for the tank though. I dont want to be making excuses but I know some healers dont know what can be removed as sometimes I see them trying to get rid of ailments that are part of mechanics and wont go away.
Whenever I play healer myself (which is rare and I've no hesitation in saying I'm still learning how to heal) I tend to ignore poison if its less than 8 seconds because its not all that efficient of a move to just prevent maybe 200 dmg tops, if a cure can do 1k. Unless of course I'm totaly goofing and Esuna isnt part of the global cooldown?
While we're on the topic of removing buffs/debuffs - I'm surprised when Monks dont remove the buffs on the enemies, especialy the ones that cast stoneskin on themselves like in FATEs as it speeds things up. Might try it later on today to see if it works on 2nd boss in wanderers palace hard mode (say if the dmg up is accidently left to the boss to absorb) as I havnt yet seen anyone do that one.