It is foreseeable that there are going to be more plugins in the future.
The plugins directory could become more intuitive if it became directly clear if a plugin is specific to the editor, the server (CDS) or the client (UA).
So it might be a good idea to think about using sub directories. For the distribution, as well as the source code:
At the moment, there don't seem to be any empty "boilerplate" (i.e. example) plugins available, so it is only natural for developers to look into existing plugins, to see how these are implemented. So having distinct sub directories for each type of plugin would make the directory more intuitive and it would be easier for developers to locate relevant plugins.