Allowing your users to run something as root inside a container should violate a security audit. And yes, Docker is almost irresponsible to continue defaulting to root.

But containers themselves should not -- there are plenty of security benefits to using containers. There is no real difference between an LXC container and a runc container besides the fact that Docker defaults to running thing as root and without user namespaces. That is obviously a bad decision, but it's not an indictment of containers as a concept.