The point I was getting at was that Solus doesn't need to be "morally grey" or "nuanced" to be a good antagonist. A straight, capital E evil villain can still be effective, dangerous, and entertaining - just because they don't have some deeply complex reason for doing what they do, something that justifies their actions from a certain point of view, or some sympathetic element to them doesn't mean they can't be enjoyable and effective villains. (Solus, despite his flippant persona, is responsible for a Calamity and the Garlean Empire's incessant antagonism. Do not forget that.)
Most of the Imperials we've met may not revel in what they do (though some do), but they clearly don't have objections to what's asked of them - or if they do, their superiors are apathetic (at best) to their concerns and they carry out their orders anyway. Considering the full scope of what their country does, does that make them evil?
The black-cloak Ascians, I agree, are evil from our perspective - but without knowing their full motives, declaring them evil for evil's sake is somewhat presumptuous. (Except Lahabrea, whose slip of the tongue in 2.55's stinger made it pretty clear he was doing what he was simply because he wanted to.) It depends on how you define evil, really.
Elidibus is the closest the Ascians have to a well-intentioned extremist, but one needs to remember that he has the same goal as the black-cloaked Ascians - even if he goes about it a different way and has a different demeanor, his ends are the exact same. What makes the black-cloaked Ascians evil, then - the means, or the end?