Masked comic book vigilantes aren't ever going to be a reality on the mean non-virtual streets of cities but on the Internet it seems we're confronted with something pretty much equivalent.
So here can consult all the old issue of Marvel and DC for a compendium of moral dilemmas and result.
Unbelievably, this is actually the case in Seattle.
Or maybe a bunch of actual researchers and government agencies working without praise while someone else writes a sensational story to take all of the credit. And the people believe it on the merits of it being the story they want to be true.
I can only see it as a win-win. Except the internet connected medical devices that are insecure which if affected by such purging bots would literally impact lives. I hope vigilante script kiddies don't get involved with good intent and cause havoc.
It all seems to start and end with technical ignorance of the typical customer. There are popular shows that help pepople choose better food, by exposing shenanigans food makers engage in. Perhaps there could be something similar for tech in the future. Something where a hacker comes on TV and makes a total ridicule of some IoT crap device, and the show uses it to constatntly repeats the basics, like changing default credentials, etc. Same schema that works with food shows, expose someone as an example and add some generally useful advice. Perhaps this might become feasible when IoT is more popular.