The vast majority of suffering within the setting exists as a direct result of Venat's actions so it's fair game to tie the likes of Ul'dah's inequality and Garlemald's conquest to the consequences of the Sundering.

Furthermore, the Garleans were only seeking to conquer other nations as a direct result of being unable to naturally manipulate aether which resulted in their land being stolen bit by bit until they were forced to do whatever was necessary in order to prevent their own extinction. Incidentally, had it not been for the Ascians giving the Garleans a helping hand they may very well have gone extinct had they not become an Empire.

Let's not forget the side quest in Amaurot which revealed that Ancients who could not manipulate aether to the same extent as their brethren were given the tools in which they could do so in the name of equality. Something, I note, which differs significantly to how the Sundered reacted to the same set of circumstances...

In other words, the Garleans were forced into an unenviable situation. Much like the Ascians, who, in an effort to prevent the extinction of their own people, sought to pursue the Rejoinings...something which is again a direct consequence of Venat inflicting genocide upon the Ancients without their consent.

The Ancients also did not put any pressure on their own to 'commit suicide'. They were an exceedingly long lived race who, when they felt themselves ready, would willingly allow their aether to return to their beloved Etheirys. Had they not done as much and had lived instead for near eternity I don't doubt that the goalposts would be moved in order to criticise them for that instead.