Thank you for sharing your thoughts, ideas and opinions.
50%+1 or something in that order: True this shouldn't be on the whole community as in all those who have powers to vote, since as you suggest: Plenty aren't active. However still, a ratio can apply based on those who voted. I'm not fond of the 50%+1 too much since the yes/no voting is equally in size when it is that close. That is why I usually like a system of 60/40, or what we do in Dutch Ltds, for important foundational changes (constitution and all), the ratio is 66%/33%... but ok we don't do that for selecting peeps. In our political system we have the measure that when constitution changes are proposed, re-elections need to be held to allow the public to vote yes/no to such proposed changes.
Supervisor Board: I get you regarding the transparency. However, we have seen in our HIVE ecosystem/community (and I've seen similar in other communities) that transparency isn't there and it can take months to years before someone decides to play detective on someone to uncover wrongdoing. That's why I think an additional elected body, or multiple thereof, is very beneficial, perhaps even required. This doesn't take away the community's powers though. I mean, the community can send not only the topic owners home, but also the supervisor board(s) members. Essentially the SB gives an additional safety measure against abusive elected peeps. But I agree with you, it shouldn't have to be, the community should understand that in a decentralised world, the community also have obligations to make sure those in power with whatever authorities are using them wisely instead of abusively. However, the reality is different though.
POS vs Individual Vote: As for chain management, a POS system works well. But not everything can be captured by code, especially not when we replace more than the existing financial system, which is where I am coming from. Let us imagine a world where we don't have country borders anymore, no central institutes and authorities, and perhaps not even a law book, I don't like to see that money/wealth is the foundation of community rulings. Therefore we must find solutions to make sure we can create a voting system based on individuals. Am not sure how far those who researching such topics are, but I can imagine we gonna end up with Smart Contract-based KYC. Nobody will be involved in the KYC other than one or a set of Smart Contracts. Such a system can create a single and unique profile for every individual, with the individual given the sole power of permission management of your profile. KYC can then be done by whatever dApp by simply querying the individual's profile with a question or set of questions to which the response is either 'yes' or 'no', without factually giving out more information. Needless to say for different types of votes, we can use different types of voting systems.