Honestly, the Garlean Empire is among my least favorite story elements in FFXIV. Despite multiple opportunities to do so, they are as flat-out generic an Evil Empire as you're likely to see in any media. From their arrogant superiority to their genocidal tendencies to their people's inexplicably unshakable loyalty to terrible leaders with shortsighted (if not outright disastrous) plans, SE has dug themselves in too deep for any kind of "oh, wait, they're not really ALL that bad" plot twist to be at all reasonable. They are a caricature, and the best way to handle Garleans from this point forward is to keep them out of the storylines as much as possible. (Heck, as has been pointed out in this thread, even the "good-guy" traitors are caricatures! Anything they do is treated as though it is good by definition, simply because they're no longer with the Garleans.) I had some hope with the introduction of Valis, but nope; his intro made it clear that there was no potential change in Garlean philosophy on the way. They pretty much explicitly said that Valis is, if anything, worse than his predecessor.

I feel the same way about the Ul'dah Nanamo assassination plotline, something with potential promise that was hideously mishandled to the point where I simply don't want to see the characters involved anymore.

The Ala Mihgans have some potential as a once-belligerent Evil Empire in their own right now brought low. I'll be fine if the Ala Mihgans get some grey-vs-grey development with different Ala Mihgan factions with different viewpoints - but when the Garleans get involved, they should be nothing more than mindless mooks for the WoL to plow through without a thought or a speck of remorse. It is how they've been developed up to this point, and we're far past the point where a token sympathetic Garlean or two can turn things around.