The sort of software you see using this license is not the sort of software anybody is likely to get sued over anyway. To say that Joe Blow is being "terribly reckless" because he licensed his vimscript that prints the weather forecast to the terminal with a license that doesn't forbid suing him seems like a gross exaggeration. He's probably more likely to get struck by lightning than to be sued by anybody using his software.

I think a lot of people forget that not all software needs to be aerospace grade shit that with licenses corporate suits think are sensible. Certainly WTFPL is not an appropriate license for every software project, but that doesn't mean it's inappropriate for all software projects.