One way to address this is some degree of homogenization. WoW is pretty saturated with the different types of class and specialization; 11 classes each with no less than 3 specs (4 for druids) with different roles and playstyle, leaving up to 34 different possible specs. If one provided unique buffs, debuffs or utility over or the other, there would be stagnation and ostracization of one of the classes (which was pretty bad in TBC and especially classic for raiding content).

They tried to remedy this a bit by homogenizing some of the utility that could be provided by one of the class:spec combos; All mages regardless of their spec could buff spell power and crit, all rogues as well as enhancement shamans buffed attack speed, elemental shamans and balance druids buffed spell speed, as well as warlocks buffed spell speed, the list goes on. Being able to do all of that without sacrificing the integrity and uniqueness of each class:spec combo is a pretty damn good feat, though it's still one of the big dividers on the playerbase that want to be the special snowflake or go back to the days of olde (vanilla WoW)

In the perspective of FFXIV, we do this to an extent with the cross class abilties (DRG, MNK and BRD also have mantra), but it's undertuned to a variety of levels due to passives (granite skin, mantra). And this hits DRG pretty badly because they themselves really have no utility other than disembowel (which is still less effective on bards because of DoTs), and IMHO doesn't really offset the fact that they're a liability to dying to unavoidable damage and have a really varied damage spectrum because of bosses spinning around.