Regarding the first point, as much as I want to see otherwise, so far it appears that Hyealyn is more Grey and Black to me. Without evience or headcanon, much of the Greyness stems mostly from Eorzea's side and the antagonist (at least the major players) have been depicted as thoroughly evil with precedents serving more to support it than oppose it.
For this example, I shall first detail Elidibus. The precedents here is the fact that Ascians in general are manipulative an underhanded. They take on the act of paragons to entice the Beast Tribes to summon thier Primals an use them to sow the seed sow discord to later reap when they ripen. Even i the seed takes several era to flowish (such as Bahamut, who the Ascians taught to summon an contain, with their payout happening 4-6 eras later). They are not the trustworthy paragons they oft pretend to be and it stands to reason that Elidibus is no exception until the story says otherwise, regardless of he agrees with his peers or not.
As for Garlemald, It stands to reason that I have to agree with Enkidoh here. The precedents are either muddled (Gaius and his Legion going rouge) or serve to prove my point (Note how Varis got the crown and what he did for celebration, that doesn't seem like someone leading a good country)
As for the "sympathetic" point, that is a double edge sword you're wielding, one that can be applied to the Skeletons in Eorzea's closets and the elepahnts in the room (or Brume in Ishgard's case. FATE reference intended)
As for your argument for them having a Freudian Excuse, I don't think can fly since for all we know, they either have none as part of the precedents or their only good reasons are to emulate the Allagan Empire (Which I think is just as comparable to Rome as Garlemald is.
The thing is, as it stands the Story seems to be having a Sympathetic POV thing (makes sense since at least Heavenward's story is Edmont's memoirs). As I mention an I;m sure you will mention on other threads, there are Skeletons in Eorzea's closet, elephants in the room and other things that show that They are not as much different from their opponents as they believe, things like Ul'Dah's Zombie Powder and use of Slaves. Limsa's Piracy, Gridania's xenophobia, Ishgard's inequality and fundamentalism amount the citizens an Ala Mhigo's Autumn War an the culture surrounding it between then and their sacking by Garlemald. The precedent is against Erorzea as much as it is Garlemald and the Ascians, but since we went to Eorzea first and saw it under attack by Garlemald... well I'm sure you know how important first impressions are right?
Now that I think about I wonder if Sins of the Ancestors is a theme in this game/expansion.
Who knows, maybe the POV will change if an only if we get other other side of the story.