What functionality is missing? What is unsatisfying with the current situation?

The current setup allows you to set up 'per-world' subscriber groups which is fantastic. However, if you have more than a few worlds, or more than a couple of groups, managing them all and ensuring you provide access to all of the appropriate groups can become a bit of a nightmare.   My proposal is this: When you create a group, have the option to click a checkbox to assign the worlds to the group assets, and then select what worlds you want to assign. This would also prevent the need to manually add one person to several different groups if they need access.   For example, if you had a group that was for your editors, or Co-DMs, and they needed access to everything, you could simply add them to the 'editor/Co-DM' group and they would get access to everything they need.   Alternatively, add a section to the Subscriber Groups Management screen that allows you to add multiple worlds to a group's assets after creating the group in a specific world.   This could also be beneficial if you have a group that plays various campaigns with the same DM. The DM could then provide access to the latest adventure, by simply adding the new world to the group's assets, rather than creating a new group altogether.   Ideally with this setup, it could also be expanded to allow specific articles from worlds outside the world you creat to be included if you want to reuse something, wither in a game, or a story you are writing.