They need to reconsider the identity of the jobs and start working from there...
I think a strong start would be getting all the jobs to be more different from each other again... Split the tanks between Physical and Magical, and make fights that focus on different things than just needing mitigation for the occasional magic damage tank buster.
Healers have kind of been completely neglected since Stormblood... And they don't even seem to remember that SCH is a Fairy themed healer by giving it an angel form...
The DPS classes do feel somewhat different, it's almost like the only work being done on gameplay is all spent on the DPS. Not on any of the other roles, or any of the fights. Everything that isn't DPS gameplay is just an afterthought.