I was given a suggestion at Topic:Unpy3y332x9rk1ji that I request some change on TemplateData to allow users to select different date formats. Here I am suggesting this especially for consistency with Wikipedia articles.
The current default format is "YYYY-MM-DD". I hope that the calendar feature would allow "DD Mon Year" and "Mon DD, Year" someday. If that is too complicated, alternatively, I made a suggestion there that an editor should have an option to manually type a date in a date parameter, similar to UploadWizard's.