The only use case I have ever used Wordpad for was to open text files with Linux End-of-Lines on a Windows computer with only Wordpad and Notepad (that do not see LF as proper and of lines and just displays one line of mess).
https://devblogs.microsoft.com/commandline/extended-eol-in-n...
Oh! Also, needing to open an RTF when Word wasn't installed.
FYI, notepad can cover this use case now, as it can handle more character encodings and line-endings.