Like @shikuz said, his example was more of a demonstration of how Jarvis can help with daily tasks, like to selectively copy and transform list or checkboxes. While I can see some real interesting use cases for that, I think it's an overkill for a shopping list.
If you keep my workflow and my CSS solution, all that's needed to make it more user friendly is a button "Hide/Show unchecked items", to avoid dabbling with CSS. A "check/uncheck all boxes" button could be useful too.