Perhaps one of the most pertinent pieces of information that isn't highlighted is the fact that there is a complex social structure in place within Cassian society, one that hasn't been fully revealed to prospective fans (and intentionally, at that; there are secrets best held back for later and for players exploring the game, after all). Malvolio mentions that he himself is a highborn Cassian, which implies that there are lowborn members of the society as well.
So is it all aristocracy? Hereditary power? Merit-based appointments? That's still under wraps, but a great deal of the social hierarchy has to do with the emperors who rule over the Dominion, beings that aren't entirely human any longer. What can be said for certain is that the social setup is very firmly entrenched and developed, with those at the top disinclined to make any major changes for those on the bottom. You know, much like any entrenched power structure in the history of anything.
If you're immediately thinking that the Exiles are somehow tied into the lowborn Cassians and that might explain Malvolio's contempt, however true that might be, it's only part of the story. Moore states that the Exile humans have been separate from the Cassian humans for around 300 years, more than enough time for distinctions about former places in Cassian society to be largely irrelevant. This isn't a case of a factional war that started taking place five months ago; this is a conflict wherein the Exiles have long since become something other than just rebellious humans.
But can you blame the Exiles? After all, the Dominion must be this oppressive place to live, right? Malvolio certainly seems unpleasant enough, the whole government must have a jackboot firmly planted on the throats of its citizens!
Except that's not the case. As it turns out, the Dominion as a rule sees its duty as one of spreading enlightenment to the galaxy, starting with its own citizens. That includes education, personal freedoms, and the opportunity for what the Cassians perceive as "lower" races to elevate themselves. As a whole, the Dominion isn't oppressive.
Unless, of course, it needs to become directly involved with something, at which point it gets very direct. Dominion citizens enjoy a free and safe life for the most part, but if the empire comes calling, you are expected to do your part without complaint. Otherwise... well, one look at the Exiles will tell you what to expect when you don't do your part.
Maybe the Cassians still aren't your thing, but that's all right. Keep your eyes peeled for more on the Draken and the Mechari next week, with more in-depth bits of lore from behind the scenes!