Right I get that, it's because the docker daemon needs root access to do its management stuff. But as far as running random "bad things" off docker hub, I always assume it's going to be fenced off. Like by default, the containers cannot read external files or open up host ports, etc. But with --privileged I guess it can do anything.
I'm a big fan of people supplying pre-built docker images because it lets me try out their software in what I assume to be a sandbox. I'm a little less wary when it comes to docker -- almost to the point of being nonchalant, running random images willy-nilly without digging into the source code even a tiny bit. Granted, that behavior is probably gonna bite me in the ass one day. But it's definitely better than the `curl http://example.com | bash -` and `sudo make install` patterns.
Whenever I see someone's instructions telling me to use `docker --network=host` or `docker --privileged`, I can't help but panic a little... "Am I going to regret running this developer's code as root on my machine?" A little justification from the OP eases my mind, that's all. Which he did :)