I feel like the problem with this is "But what if the others are good right now?"
PLD and GNB are honestly in pretty good spots right now, WAR's main problem is it's a bit too powerful in AOE situations. DRK is the odd man out. It'd be like looking at Casters and saying, "Well, SMN is kind of lacking right now while BLM and RDM feel good...so obviously we need to rework all three, can't do just one, we need to go all the way."
GNB is not extremely overpowered but its kit is solid and consistent. It has nothing that makes things a cakewalk, but it has the tools it needs to succeed, with a strong offensive kit and functional defensive kit.
PLD is slightly underpowered offensively but somewhat overpowered defensively, neither so much that it breaks the Job, so it works well. It has strong party utility and healing tools with Clemency, but requiring a conscious choice to forego damage if you want to be a temp healer.
WAR's kit works great. Its healing is a kind of overpowered in AOE situations due to how Raw Intuition/Nascent Flash work, but in single target fights (Extremes/Savages), that is considerably cut down to size. I still have no idea why Shake It Off got buffed, though.
Compared to those, you then have DRK. DRK has WAR's playstyle with GNB's defensive utility, and people constantly asking for it to be different than WAR...while asking for it to have WAR's tools.
I DO feel that Tanks are overall too powerful in terms of sustain right now, but I'm not sure the answer is so much "throw them all out" as it is "lower the power level of those overall tools". DRK, on the other hand, has the unique problem of needing to be/do something unique and, right now, it doesn't other than TBN.
EDIT:
I'm consistently confused by people saying SUMMONER has no design space to go in. Like, I honestly have no idea how that makes sense to people conceptually.
It's the opposite problem: It's got so much space, with the problem being the Devs needing to fill it.
The Primal system (Gemshine/Precious Brilliance/Astral Flow) is extremely open-ended, since you could do anything with it. We have just three examples, and for all they're lambasted, they're all unique. We have examples of long cast time spells, normal cast time spells, instant cast spells, and a 1-2 melee combo. Aside from that, we've also seen Ruin/Outburst repurposed (by the Demis), meaning they could extend that to Primals in the future as well to create additional effects. It is probably the single most open-ended Job in the game right now. That is the exact opposite of "not much design space available".
That's also not BRD's problem, honestly. BRD's problem is it is aimeless. Its focus is all over the place, but not in any cohesive way, making it a lot like old SMN that KIND of worked, but was a total accident of nature rather than arriving at its place through good and deliberate design decisions.
I just see this wording a lot, and it makes zero sense. SMN is probably the most open-ended Job right now due to how it is set up and what all could be added, as well as room for plenty of flavor. It could literally grab into BLU and just rob it blind of some things like Ravana's 4 hit attack (which is not much different than Garuda, yet that one is praised for...reasons; yes yes, the way it buffs, but in practice, that's how it's used). Not to mention they could someday go wild and do things like Eden double-summoning or Stocking for later (FF8 aside).
It's okay to say one doesn't like SMN because they find it too simplistic, but saying it has no design space is just...I dunno, doesn't make sense, I guess.