I really like your idea about a plugin and would definitely be up for that. It reminds me of what Alan LevineAlan Levine has done with the Splots Writer plugin. This is also how EdublogsEdublogs have built wikis their version of WordPress.
Doing this set up as a theme and leveraging posts seems like a very odd choice. From my reading, Mike Caulfield was relatively new to WordPress development when he made this. Even if he was an intermediate developer, he should be proud of his effort, including his attention to some minute bits of UI that others wouldn’t have considered. To make this a more ubiquitous solution, it may have been a better choice to create it as a plugin, do a custom post type for wiki cards and create a separate section of the database for them instead of trying to leverage posts. This way it could have been installed on any pre-existing WordPress install and the user could choose their own favorite theme and still have a wiki built into it. In this incarnation it’s really only meant to be installed on a fresh stand-alone site.