I think that Codes of Conduct have their purpose, which is different for each kind of group listed in the question: companies, organizations, and communities. Obviously, companies need to provide some form of a code of conduct; their human resources department probably requires it. In a company, this is very useful. A code of conduct can help ensure a comfortable working environment, and thus keep employee productivity high. In a smaller community, such as an open source project, I believe the value of the Code of Conduct diminishes significantly. At a company, workers are spending a large amount of their time together. More importantly, they must share resources such as bathrooms and fridges. In an open source community, where all communication happens online, this is not an issue. Therefore, the scope of the code of conduct is diminished significantly. It is now attempting to regulate simple textual communications. This reminds me of the statistic that words only compromise 10% of human communication, with the other 90% being boy language and tone. Similarly, the vast majority of the usefulness of a code of conduct lies in its discussion of physical interactions and workplace etiquette, as opposed to textual conversation. I am of the opinion that most communities do not need an explicit code of conduct as such, but can rather rely on their community leaders or moderators to ensure a productive and valuable environment.
That is not to say that a simple code of conduct is invaluable to these groups. However, looking at some of the resources provided, these codes try to cover a much larger amount of topics than I think are necessary. The Apache and Linux kernel codes of conduct are good examples of simple, to the point discussions on community behavior. These are in stark contrast to the Geek Feminism code of conduct called out in the article “An anonymous response to dangerous FOSS Codes of Conduct” which attempts to explicitly list as many possible forms of inappropriate behavior as possible (ex: “simulated physical contact”). This is a losing battle, and it is better to rely on the community to create an air of collaboration than to bring up as many points as possible and threaten retribution. This instead creates an air of fear in the community as members attempt to ensure they are not breaking any rules. Furthermore, relying on moderators and the community at large as opposed to a document is a much more versatile approach, as it allows new standards and expectations to be ingrained in the identity of the group as quickly as the people can agree, as opposed to the alternatives of either altering the code on a consistent basis (probably with some form of voting or other oversight) or simply not paying attention to change at all. That is why I believe that it is best for online communities to have a short, general code of conduct as opposed to a list of laws. To liken it to government, I prefer the judiciary to the penal system.