Agreed the demo object is silly, but they are problems that are hard to solve without GUI automation. For example, this tool could be great for scrapping flash-based websites, which are notoriously painful to automate. And the integration with python means that you can easily mix and match with conditional statements, calls to OCR libraries, etc...
From my (admitedly limited) web frameworks experience (django, grails and catayst), catalyst indeed shines by the extreme level of freedom in the choice it leaves up to you. If you're willing to invest the time necessary, it is indeed a great way to get separation of concerns without commiting to a specific way of programming your webapps. If you're used to glueing together modules in your apps, you should fit right in.