"Popular and erroneous conceptions of the time period"? What do you mean by that? Are you getting political? I am talking about game mechanics, if you want to talk politics go to politics forum.
The disjointed mechanics I am talking about are a thing for European nations just as much, if not more. Take Brandenburg for example, do we really need "militarization", when we already have army tradition and army professionalism? Whats is it good for except infantile "dude, Prussian space marines, lmao"? Wouldnt it be better, if we instead got something that simulates the ugly bits of war instead of celebrating epic Preussen supersoldaten? War exhaustion as it is sucks, because you can cure it with mana and the only way to cause permanent damage through looting is pillaging the capital. Now look at meiou, they managed to jury-rig a pop system on top of EU4, where every soldier you lose is a person that dies. Why cant we have that in vanilla?
A well designed deep mechanic makes gameplay more interesting globally, they are not "European flavour". Like when I was playing Incas myself, I had a fairly formidable army just a level or two in tech behind the Spanish and yet the Spanish could roflstomp me by sheer size of their doomstacks. A good mechanic for logistics would limit the European naval invasion forces and improve survival rates for nations around the world that could then beat them through vastly superiour local numbers.
Fact is that Europe was the pivotal continent of this time period, Europeans were OP historically and should be OP in the game. Question is how do you simulate this, EU3 did it with blatant "Europeans are just better people, lol" approach by giving tech debuffs to non europeans, EU4 ATM tries to do the same thing using institution spawning but just fails at its job and everyone around the world ends up with simmiliar tech levels. While being more complex mechanically than the chauvinistic model of EU3, it is not better in its current state.
most people don't play mods
And most people dont play non-European nations. That point doesnt really bode well with the rest of your argument.
My argument here is that flavour is better done through mods, because its much easier to program content than it is to program mechanics. And often user made flavour will reach superiour quality, because modders tend to be very passionate and dig deeper into history than the devs do and they also have greater artistic license for high-fantasy scenarios like native Americans surviving the Colombian onslaught. Or for example look at Third Rome Russian mechanics and strip them of the aesthetics, is there really anything specifically Russian about magically spawning large amount of high quality infrantry? Or magically supressing all rebel factions? Or the icon mechanic? Its just random buffs available uniquely for your nation that practically dont come with any impactful drawbacks. Its clearly not something that was designed with passion for eastern european or Russian history.
Its like that for everyone, the flavour is 80-90% buffs, which in turn makes nations without flavour relatively weaker, prompting the devs to give them flavour to balance things out resulting in power creep and feature bloat over long term development. That is the damn point, I was making with my criticism of the DLC philosophy. The sales model just forces the devs into making this shallow detachable expansions and the base game is being upgraded only as afterthrought.