At work, we have someone responsible for the documentation. It’s not a developer. We also have what we call a Proxy customer. Someone who represents a typical user. A good dialog between us all allows the documentation person to write stuff which conveys the developer’s knowledge of the product in a way that is useful for the user.
Here, we may want to create a mechanism that encourages the creation of such teams for each plugin.
As a start, we may want to allow a way to very visibly flag plugins that the users find difficult to use because of a poor documentation.
That would encourage people to gather as a team around it and to start a good and productive discussion with the developer. One or several people could volunteer to write the doc, based on the decisions the group makes on the wording.
That should not be so difficult. And it benefits everyone : the developer sees their plugin getting more exposure and possibly getting more popular. The users get the info they need. The people helping get credited.
Actually, a Wiki may work well for this.