Since the late 90's early 00's when Linux won the data center. Most people became really enjoyed the we don't break user land motto.
Once a kernel interface went live, it stayed that way. Ugly spots and all. Containers are starting to become a fairly important part of IT/Cloud infrastructure. Easily compariable to the OS itself. Logically those involved with maintainence would demand the same.
Yes I'm aware Docker is more a control program for interacting with Cgroups, setting quotas, installing packages, and isolating processes. Not the OS itself. It is an abstraction over the OS, hence for most developers it feels like part of the OS. So logically they'd demand it be as robust as the OS.