Why do the devs hate MCH so much?

[Shurrikhan]

Proper balance is making sure no job is unplayable, or one is vastly superior to others

Then I guess we're at proper balance already?

We have 5 jobs that are presently slightly undertuned, with MCH being the outlier in having no utility beyond its hypermobility (which is of far less [relative] use in modern encounters).

For the majority of percentiles, though, or even just if keeping analysis mindful of biasing at the high end, the top and bottom fall within ~7% of each other.

That said, if the devs aren't willing to offer a skill ceiling to a given class, and that design choice would cause its users to approach the relative performance of its skill ceiling that much faster, it's not reasonable to expect that it could be balanced perfectly even at the highest end of things without being overtuned below that. And a single overpowered job does a heck of a lot more harm on the average player's perceived freedom to play what all they want than a single underpowered one. (Which is not to say that either is okay.)

Tl;dr: MCH, DNC, BRD, SMN, and RDM need very slight buffs. MCH may need slightly more than the rest, even. But jobs like MCH could just as greatly benefit from further depth / a higher skill ceiling if they want tighter high-end balance without creating new and worse balance problems below that point.

And it's not vast. MCHs competition is DNC and BRD. The difference is not vast.

That relies on the bail-outs of arbitrary sub-role assignments, which in turn essentially means that Physical Ranged are the only sub-role a party is discouraged from taking two of.

Granted, that also belies the whole mess of physical ranged being, these days, a wholly arbitrary sub-role in the first place that makes no more sense now than, say, randomly splitting NIN and DRG from MNK, RPR, and SAM.