I don’t disagree with your assessment, but I’m sad that the 40K universe can’t be interpreted for what it is. The whole point is that there are no good guys, only flavors of galaxy-scale horror. It makes sense from a game design standpoint because you’re supposed to give up the idea that you’re furthering a righteous cause or participating in an evolving narrative. You’re just controlling an army against another army in one of countless battles that have no real consequence because there’s always another army and another battle. They state it right up front: “In the grim darkness of the far future, there is only war.” In that context, there can’t be any good guys, just different factions in an endless struggle.

But yeah, they don’t do a good enough job of reminding fans that the Imperium is only relatable because it has a human face, and is otherwise indistinguishable from any of the other factions in terms of being comically evil.