The use case for Web Flow is to solve the problem involved with controller logic that spans multiple-page navigation (a pageflow, or wizard). If you don't have to have a form split across multiple pages (or need several small forms to participate in a single transaction), you probably don't need a Pageflow.
Most applications do need this, however. Anything more than simple CRUD stands to benefit.
Pageflows provide a natural cache for the data and can solve problems involved otherwise when using back button navigation and multiple frames/tabs.
If you are thinking about how to store data that needs to live longer than a single request (the common but misguided view is to store in the HttpSession) then you will definitely get something out of Web Flow. If you're not doing anything like that and processing everything at the request-scope then odds are you don't need Web Flow.
Update:
Web Flow can eliminate the need for specialized controller classes to accomplish following a path of page transitions/form updates along a predefined workflow. If you don't need to do this, you can save yourself a lot of configuration/complexity just by using MVC.