when you run a polyglot stack with java/python/go/node on top of a cluster of machines, you will love to have them containerized and uniform. It makes scripting and CI so much easier.

or, when you have a legacy app that relies on java 6, but you want everything else to run on java 8, the ability to drop everything into a container with its runtime is a life saver.

source: I'm the devops person that's responsible for making this work