UI controllers will be overriding that method to pull the server or wc from the editor. We can't cache it in a local variable because the UI controllers will be requiring the most up-to-date version from the editor (since the editor can change, save, etc, and a new working copy will be available).   For now, any subsystem impl is initialized with a server or working copy, and that is a requirement for using the subsystem. The ui subsystems will override the getters to pull from other models, but will still be unable to cache it.