In support of this theory, there IS an in-game example of a Hearer using their influence to throw their weight around, with the implication that the decrees he was laying down were his own self-righteousness at work rather than any actual whisper from an Elemental. The Stormblood Leatherworker quests feature just such a Hearer, who finds the taxidermy we practise during that questline to be personally distasteful, and uses his influence to put an end to it. So it's at least POSSIBLE that the plight of the Ala Mhigans was a plot by a bigoted Hearer who wants them run out of town - but there are few or no clues in the quest dialogue to support this interpretation.
The Elementals have a weird relationship with the WoL that doesn't always make sense. The WoL can apparently do whatever they damn well please in the Shroud, and we never get any flack for it.
There's some evidence that the Elementals are less powerful than they used to be, following the Seventh Calamity. It's possible that the Elementals are a whole lot less able to bare their teeth than they used to be, but the Gridanians are hesitant to test their limits anyway. They know what the Elementals can be like when they're at their worst, after all - is it worth the risk to start rebelling, just in case they MIGHT be more passive than they were before?
I'm also of the opinion that the "worst" the Gridanians are so fearful of (basically, the Great Flood of the Sixth Calamity, which the elemental Oha Sok unleashed upon the world to end the War of the Magi), can never actually be repeated - at least, not to the same degree. We've since learned that the disasters of each Calamity have been massively magnified by the flood of Aether from a Rejoining world. While it's likely Oha Sok could have caused a lot of damage on its own, the Rejoining is what caused it to become a flood large enough to put an end to all civilization in Eorzea.
It may well be that the Gridanians are on more equal footing with the Elementals, now - but it's entirely sensible that they'd approach this possibility with an enormous amount of caution!
You left "Systemic oppression of the natives" off the list! XD Each nation has its dark side, no doubt about it.Gridania may be one of the most pleasant areas geographically, but its got some real drawbacks. Gimme my freedom loving ruffians, volcanic isles, and Mediterranean climate with a mild chance of earthquakes and tidal waves, anytime. lol