I think the biggest problem with the system is the huge variance in RP's you can get depending on the population and literacy of the target. Maxing out on RP's after taking Korea is a bit too good, while getting almost nothing when taking a little 20,000 population country in the Middle East or Africa sucks a bit too much. This is because the limiting mechanic is infamy, but infamy is tied to the number of states you conquer (if anything) rather than their population. It would be nice if they reworked the mechanic to provide RP that scales on the number of states or regions taken instead. It would tone down China and Japan while giving other uncivs have more rewarding paths to civilizing.