Why Ethereum? Some thoughts on the value, potential and end goals of smart contract enabled blockchains
Why have smart contract blockchains? why not just have a centralized authority be trusted and elected and have them govern?
If your civilization can afford it, blockchains are better. while more complex and energy intensive they are formal and incorruptible which are good traits for systems of rules. the question "why blockchains? why not a trusted governing body?" is analogous to, in ancient times, asking "why write down the laws? why not just have good leaders and have them make all the decisions?". the idea of a good king is a simple and intuitive way to have a governance system but history demonstrates that in practice this governance system often goes awry: "power corrupts and absolute power corrupts absolutely". it's better to write down your laws so you can at least cross reference the actions of your governing executives and citizenry with the letter of the law. perhaps you even develop a separate system of governance that checks to see if the executives are upholding the law. also having laws that are written down allows people to have some sense of what to expect from their leaders and society.
the promise of blockchain (specifically ones that allow for smart contracts) is to elevate governance from written law to one of deterministic code. Ethereum, if successful, will change how humans govern themselves and allow for more complex human social systems to emerge and interoperate.