I think I am getting a hang of the direction Oda is going regarding the grey areas of void century.
In our real world, there are two prevalent socio-economical ideas, capitalism and socialism,which are seemingly conflicting but each claims to bring upliftment of the society in it's own way. Also, an ardent supporter of one idea never acknowledges the other.
Perhaps Oda's world also faced the similar dilemma during the void century. 20 kings were trying to preserve the status quo and this preserving their own unique heritage and culture (capitalist mindset)while Ancient Kingdom was aiming for a single kingdom worldwide where everyone work for common goals( communist thinking).
Even in our world, capitalism always exploit common people while historically communism has had been apathetic to people's aspiration and cultural roots.
I think Oda may cook along these lines.