Let’s say you create a module and set all your settings, and now you want to use it globally, but you want to be able to change the contents of that global module without changing the content on all other places it’s used on. - you can’t
Right now it’s either Global everything or not global at all. In many cases I’ve used the same module on several pages, and later have to manually go into the module on each and every page and change settings.
Basically - Content not global, but settings are. Re-usable global modules with no fixed content.