Building web applications today involves writing a lot of repetitive code. Frameworks and snippets take reduce some of this right off that bat, however we can take this a step further. We FW/1's new subsystem architecture to make whole workflows reusable as modules.
By modularizing your code you can not only reuse it for other projects with minimal work, you can also share fixes and improvements between projects that use the same module automatically.
In addition you simplify your code base by breaking you monolith down into discrete segments which you can then dedicate developers to without those developer needing to know the intricacies of the parent applications the module will integrate with later on.