I think a powerful, centralized, and stable (across transitions of power, especially) state is likely a necessary pre-requisite to focused economic development

I think a powerful, centralized, and stable (across transitions of power, especially) state is likely a necessary pre-requisite to focused economic development across larger kingdoms. Otherwise there's too much temptation to treat parts of "your" territory as potentially part of a future rebel state you (or one of your children) will have to fight for control of the crown, because there's a really good chance that will in fact happen at some point in the not-so-distant future. Might be better to undermine the development of some of them, even. Not a great environment for cohesive, grand, long-term economic planning. Gotta quash the infighting, gotta get the inheritance laws sorted out so the crown's territory's not being carved up all the time among kids who'll often end up going to war with one another. Then the serious economic development can start. I think that's one of the key differences between how a monarch of France and a monarch of Spain, say, would have approached economic development, around the time Spain was starting to get serious about the whole nation-state thing. I think there may actually have been different incentives and motivations driving less-effective patterns of economic development in less-centralized or less-internally-secure states, caused, more or less, by differences in effective state power. I'm not sure how politically stable and internally secure Eastern states were then, but my guess would be less so than what Spain was beginning to achieve.