I'm only pointing out that docker has some pretty big UX problems as a whole (whether or not they can reduce the complexity of them enough to actually solve them is another thing). I wouldn't bill docker's UX as it's killer feature.
Docker's UX is not a feature, it's just part of its DNA that assisted in gaining rapid mindshare, sort of like Vagrant before it, by being more approachable than older tools like OpenVZ and VirtualBox respectively.
