I notice that you are not mentioning a couple of the most important benefits of decentralization. The economics of violence with a non-physical measure of value does not provide a return on the investment of the cost of violence. Centralization happened historically because physical defense of physical assets was best accomplished by centralizing power with those most adept at physically protecting their assets from other groups that would use their superior force to steal from individuals acting on their own.
Decentralization provides no point of attack for theft and control through violent means and as Trace Mayer put it, "no amount of force can solve a math problem". These newly evolved virtual measurements of value are outside of the reach of the "bullies", whether call them Mafia, Robber Barons, or Nation-States. Your depiction of the centralized building of the pyramids is most appropriate, it was through threat of violence and the resulting enslavement of masses of people that enabled their creation of those physical structures.
Their "centralization of force" is no longer cost effective, they just don't realize it yet and as I put it, "The Bankster Emperors are Naked". But this fact will not be televised, it must be realized on a personal level, and many lifelong subjects of the existing Nanny-States have trouble even considering permission-less behavior, let alone believing that the threat of violence is an empty one.
That being said, I consider myself a Taoist Cryptobanker, and believe that a balancing of these polarizing forces is necessary for enduring stability and there is sometimes a place for centralized systems (for example with the tokenization of real world assets like real estate or precious metals, as physical assets require trusted custodians, otherwise we're dealing with more paper fictions that also must be trusted. It is the oracles validating the real world information that requires centralization, and for purely virtual assets like BTC or STEEM, the decentralized nodes provide that validation service.
RE: Understanding blockchain's social impact