Edit: Also it seems to me that the Imperium as a whole should be more Nurgle aligned. The most interesting and dynamic people places and events would be more Khorn, Tzeentch, or Slaanesh. But the average bog standard uncounted trillionth person seems like death and decay would be their thing more then the others.
The Imperium's activities feed all the Ruinous Powers about equally. Nurgle is as you said, but in particular it's those who have accepted death and decay, who have given into the void and tried to love their place in life. Slaanesh is fueled by the opposite, by the extremism that the Imperium's people sometimes engage in to try and give their lives meaning. Tzeentch is fueled by the rat race, the endless powergames that Imperials play against one another. And Khorne, well...you know the line.
Hum, interesting. I suppose my view of imperial society is that it's largely stagnant and unchanging, and most peoples lives are within it as well. A world that survives 1000 years in roughly the same state seems one where most people are also not hugely dynamic. A factory worker who works in the same factory making the same bullets that his greatx23 grandfather made, it seems like a life of stagnation that eventually leads to death would be a life for Nurgle on the whole, even though it's certainly going to be filled with points for any chaos god. Accepting the Imperial creed and spending your life as a good cog in the machine seems to be a thing that'd fit Nurgle, but I guess that's not really embracing or consciously accepting it? So maybe it doesn't count enough for Nurgle.
Or maybe my view of how dynamic the average person in the warhammer world is flawed... Potentially worlds do change and shift more then I was aware of and the average was just that, an average. The time scale that the imperium has existed on seems so huge to me though that it's hard for me to imagine places within it as dynamic.
Stagnant yes, but hardly unchanging. Consider the following: Rebellion is not properly a crime in the Imperium. Heresy is a crime. Treason is a crime. But knocking over the planetary government is only criminal if you fail. If you succeed? As long as you follow the Imperium's few galactic laws, they'll endorse your rule. Put all your friends in the nobility, execute the nobility and hold elections, whatever you want. Hell, if the old government was lagging on their tithe the Imperium might fund your rebellion. Victory is the surest sign of the Emperor's favor.
It's true that powerful people have an easy time controlling and harming powerless people, just like in reality. But it's also true that power can slip right through your fingers at the slightest lapse, that most power is only what people think you have, and that the most powerful person in the world can still be stabbed to death as they sleep. Holding onto power in the Imperium is intrigue without end.
Being a peasant doesn't mean that great of a life, but that doesn't mean all you do is sit around carving bolter shells all day. I mean, some people do that, but so many are also gangers, are hive vendors, are trying to take advantage of that forged spire pass that this guy your uncle knows got you in exchange for drawing some weird graffiti.
That's the whole reason people start turning to Chaos, in fact. You can have power, have excitement, have a dynamic life and in exchange for not that much. Hell, in exchange for things that you already
want to do, even.