The concept of widgets is awesome! You just need to drop them onto pages. But in order to create a full blown application with multiple pages/connected widgets, there needs to be an ability so that when you add an App to a website, it creates specific pages for the website designer so they don't have to do it individually by creating a page for each widget. There should be an option to make a widget into a page. These pages would be just like regular site pages, except directly connected to the app. In the App Builder, SEO things could also be set up.