It's not being free of the Ascians that allows Garlemald to heal, though. It's being free of any form of government whatsoever. This is evident from the actions of the Legates in EW; even with the Empire in such a shattered state, the military-based government was still operating under the core value of war. Garlemald was, first and foremost, a military dictatorship that respected only martial strength; most other industries and facets of its society were likewise judged by how useful they were to their military operations. This absolute faith in military might also determined who ruled the country as general-in-chief (Solus and Varis both earned their crowns through military might, and part of the reason the country fell is because the Legates went to war with each other over a power vacuum).

Even being reduced to a crippled, hopelessly underpowered military wasn't enough to deter most of Garlemald from their ways -- the whole point of the Anima primal was that the people were sure that their warrior king Varis was still alive and would unite the military, punish the traitors, drive out the foreign occupiers, and restore the Empire's hold on Eitherys. It's not until Anima is dead, their Legates have all surrendered or killed themselves, and there is absolutely zero hope of restoring the Empire to what it was that the surviving Garlean populace takes any steps in an alternate direction.

My problem with the "why we choose to act" viewpoint is because, as proven by the Garleans, most people don't even know why themselves, especially after they've been doing it for a long time. Whatever initial motives they had (sympathetic or not) are quickly irrelevant outside of propaganda -- tradition becomes all they know, and any other way of life seems impossible or insulting.