Public choice theory studies such questions, and if this question really interests you, I suggest digging around. As you might expect, there are researchers who have devoted years of their lives to such questions. The Calculus of Consent is a very good starting point (and something to come back to later; it's very deep). The Tiebout model might interest you.
"How governments work" and "how to make governments work well" are questions people have been very interested in for a long time, and any serious attempt at an answer would have to begin by familiarizing oneself with the literature.
I am not persuaded by your history of the 20th century, by the way. Why should war have ever been necessary? Trade exists. Surely your own cited example of the Dutch success in the 17th century is one such example.
Why should war have ever been necessary?
In nature, when habitat’s population exceeds the carrying capacity, animals can either starve or try to invade the neighboring habitats. Before industrial revolution the human choices were no different.
Historically, the evolution of government systems was mainly driven by violence, with invasions and revolutions being the principal agents of selection process. The rules of the game were predetermined by our environment - land was a limited resource, for which our ancestors had to compete, if only to ensure the survival of their descendants.
The 20th century introduced a game changer. As agricultural productivity in developed countries rose by orders of magnitude and natural population growth practically came to a halt, possessing a large territory stopped being a necessity. Countries with little arable land, ultra-high population density and no natural resources can now not only feed their population, but also achieve top living standards. These changes may open a fundamentally different route for societal evolution – one that would not be based on violence or compulsion.
A small thought experiment - imagine what would happen if central governments cede most powers to smaller territorial units:
Unfortunately, there are serious obstacles to the successful implementation of this idea:
Do you think these problems are solvable?