I responded on the talk page, but to comment here as well: while interesting and potentially useful of its own, the last-edit trick is completely unrelated to what date= is intended for. If we want to add that, great. If we want to remove date=, fine. But we need to be clear that changing from date= to last-edit isn't simply a technical change. It's a significant change in what information is being provided and it removes the ability to provide the table on the category page.
