Much is lost in translation in a discussion about decentralization versus centralization, and there are no clear boundaries, but I understand the basic premise that inviting more people into a decision-making process theoretically yields better results for the whole. However, within any attempt at decentralization it's important to enforce protections for personal rights from the tyranny of the majority, and this enforcement will inevitably be through a centralized authority. For example, freedom of speech may be a so-called right in the US Constitution and STEEM blockchain, but it needs to be enforced by the government in the US or various front-ends on the STEEM blockchain to be useful.
The best governance models have the most hard-coded rights for the users, balanced distribution of power, and a high turnover rate for people in power. I can see on your blog you already understand how easily the witness spots can be bought and the inevitable self-preserving behavior that we will see from them. The witness system needs an overhaul, and specific proposals for how to accomplish this have been presented by authors in better position than I am. I think witness earnings should be distributed to more accounts in a way that scales with STEEM price to provide less profit incentive, but it would essentially require those in positions of power voting against what they think is their self-interest.