I use AppZapper and recommend it to less technical friends who don't want to figure out how to make Hazel effective (I use both.) I'd have to agree that I don't see much need to upgrade AppZapper (or Disco for that matter) because it does exactly what it says and works great. If it ain't broke...
There are many apps that (IMHO) only need updates when a new OS version comes out so that they continue to provide full functionality. AppZapper, Disco, Scrivener, TextMate, and other workhorse programs fit this category. I don't want my hammer suddenly developing a screwdriver feature; I just want a good hammer that I can pick up and use without thinking about it.
CARS is (mostly) dead. Long Live CANS!