Whilst for major upgrades that might make sense, what about instances like a high risk security fix where upgrade speed is important... People don't want to be re-building from scratch in that kind of setup...
I fully understand your issue. Creating a new cluster means for me running a script that sets up a new cluster in ~15min. There is https://github.com/apprenda/kismatic which can help simplify your cluster setup if you run in a enterprise environment.
You can also take a look at https://coreos.com/tectonic where coreos provides a enterprise kubernetes distribution that supports updating a kubernetes cluster without downtime but I personally haven't tested tectonic.
You can also take a look at https://coreos.com/tectonic where coreos provides a enterprise kubernetes distribution that supports updating a kubernetes cluster without downtime but I personally haven't tested tectonic.