This seems a little unrealistic, does it not? For example, you might get voted in or out based on other actions you are taking, general popularity, etc. Sounds like politics to me.

Yeah, whenever there is something to vote, there is politics. But if the description of a job is very narrow, politics will have very little influence.

From the decentralization perspective, we should also remember that we can't vote only great individuals as witnesses, but we have to see what is the set of witnesses overall. If all witnesses are, for example, from the same jurisdiction, that might be a problem. We should have a diverse set of witnesses from all over the world. Some anonymous, some well-known companies and individuals.

Thanks for the explanation of Bitshares. However, I still see little benefit in not just requiring that committee members just run a node and sign blocks. The role of a pure 'witness' seems redundant to me.

Of course that will work, too. But I'm inclined to think about long-term future so I want a system that can work in different situations and with different people. We don't know what's going to happen, so it's better to plan the system to endure stormy times and to be resilient.

Also, the ideal committee member is businessman, academic, or economist, who understands how economic incentives influence users on the platform. They might not be people who know how to run a server.

Also, who decides on hard forks in Bitshares?

Good question, I'm not sure actually. I stopped following it when Steem was launched. I think hardforks mostly just happened without much problems because the dev team listened to the community and didn't try to push controversial changes. At least once there were a worker proposal that was used to ask for an opinion from the stakeholders whether or not a certain change should be implemented.