The main use case brought up is supporting people still on Win XP SP2 (released in August 2004), when the answer should be for them to upgrade to something newer, either OS or browser.
That said, there are probably a lot of embedded systems of similar ancient vintage that may not be easily upgradable. The wisdom of having them internet connected is questionable at best.
It appears that this really works best with CloudFlare's systems - if you're looking to set up your own CA, and want help working through all the openssl commands and configuration files, this is pretty helpful: