I think it's worth pointing out that even when WHM wasn't as OP as SCH in ARR, AST in 3.4+ HW, or really special at all in 4.x, most players still played WHM for whatever variety of factors, be that ease of use, accessible from level 1 or classic FF nostalgia.

This was fine. WHM was *never* in a position where it could not complete content, like AST in early HW. I think the imbalance in performance is natural, especially if they insist that only half the jobs in the role can contribute to the meta 2 min group buffs (no tanks have been able to directly buff another job's damage since 5.0). It was always viable.

But, near balance in playstyle is the problem, because that's where the homogeny hurts the players.

Their 'play any job you want' system is at its most broadly appealing when each job within a role manages to do this:

Viable in performance, diverse in gameplay.