The problems you bring up are all valid. Many of the solutions you mention would be valid as well except that in my time here generally speaking Steemit Inc does not want the project to be decentralized. Their developers make all the real decisions on what will and will not be allowed into steem. The people who say that the witnesses decide what code to run are living in a fantasy land because to my knowledge the witnesses have never once run code that did not come from steemit and the steemit repo. I think maybe a hard fork away is what is needed to save STEEM. The key is to do it in a way that whales allow it or else it has no hope of happening.