Modules are good if you want to reuse them in multiple applications or when the part of the application is large enough to guarantee separation into your piece. Instead of having a bunch of unconnected controllers in one directory, the module allows you to split MVC into related pieces.
We constantly use modules; Our customers often choose between the available modules for packaging the application. We also introduced module dependencies so that the modules can rely on each other.
As a rule, when our applications have a high-level subfolder, if they have not only a couple of pages, these are modules. For example, About will only be the controller and presentation in the application, but the forum can be its own module.