Well, if the ARW fails and the French Revolution is both significantly delayed and curbed, then (very broadly and roughly speaking) the legacy of the Enlightenment is going to be much weaker in the subsequent 19th Century. As an example, I can see Republicanism in TTL not only being much weaker, but developing in conflict with what OTL would consider other socially progressive values (abolitionism, social welfare, gender equality, etc).
The problem with a lot of those ideals is they're basically Pandora's box. You can't put the ideas back in. You can defeat the French Revolution, but if you get the same conditions which produced it (inevitable), can you prevent it again?
Plus there's always enlightened absolutism for continuing to advance Enlightenment ideals.
Make the colonization process slow and steady, perhaps, and put it under the oversight of the elite, who teach the natives the ways of imperialist oppression?
It isn't like they needed much teaching, since OTL dictators like Macias Nguema and Mobutu brought out the worst tendencies of African rule and applied it to "modern" states. For the North Americans, they seemed to have done pretty well in their own right by how they treated subdued people. The Sioux in particular seem to have done well in abusing tribes who submitted to them, so much that the Pawnee chose to voluntarily relocate to Indian Territory in large part because of them. Although of course the rule of the Sioux was far different and occurred in far different contexts than the aforementioned African dictators, they still had the capacity to be plenty nasty. How would that apply in a modern industrial/post-industrial society when mass murder and brutal exploitation is easier than ever? I don't know.
OTL is rather horrifying when you look at it a certain way.
I mean:
China. Pretty much always the largest and often the most sophisticated state for the past 2000 years, periodically goes through massive civil war and/or foreign invasion which routinely kills tens or hundreds of millions of people even in the Middle Ages.
The Taping Rebellion and Mongol invasions both killed more people than the First World War, and depending on the estimates the former may have even exceeded the second in total body count.
Basically right. OTL has huge amounts of dystopic moments.
China is of special note since basically all of the most deadly wars of all time involved China in some form or another, and Chinese made up the majority of the death toll. China might as well have been a dystopia considering the hard life of the vast majority of the people and as you mentioned, periodic warfare which kills millions. I'd add natural disasters too, of which the most deadly tend to involve China (earthquakes, floods, etc.). There's also the 1938 Huang He flood which shows that these natural disasters of insane death tolls can be induced artificially. There's also been studies showing that hydroelectric power can play a role in earthquakes, such as the 2008 Sichuan quake.
The OP rules out natural disasters, but if you have people frequently triggering them and completely ignoring environmental concerns because of the international order, that's a good step towards dystopia, since in places like China or India, you're bound to be easily able to kill thousands, if not hundreds of thousands.