This would work horribly bad in EU3 mostly because of sliders and stuff like that. AI in EU3 is simply not designed to make such choices. Maybe it could be done for an entirely new game, meaning countries perform according to their success in various fields, but the way i see it, its mostly unneeded ovecomplication of the things, and it looks like game designers want to keep things as simple as possible. This inevitably leads to linearity creeping behind most core mechanics.
If EU3 was a single era game - like CK2 - then there would no problem implementing what you ask for, as you can see from the actual CK2 example, where all power countries have at their disposal comes from land, and how you govern it, apart from start tech spread out which is scripted, everything else develops entirely based on context.
However, like i said already, i dont think this is something that would work out well in EU game. Yes, it would be nice to have ability to mod a system like that, and observe world develop in different ways (what if an Indian state had a different mindset in certain fields). For a vanilla EU game as a developer, i fear, what you want is consistency in performance, and consistency in way the world develops, and in this sense (in EU3 at least) western Europe is crucial, because its basically the only place where AI will choose QFTNW idea, so if you want colonial game to ever happen (Americas being colonized) you want a group of standard 5 countries to "succeed" in 95% of played games (England, Castille, Portugal, France and Holland). My guess is that this is the whole reason why in EU3 there is so much linearity, specially when it comes to techs.
