We'll want to maintain and install a copy of the icons that we use.
Kube does not work with system icons and it's whole design depends on having the right icons available.
Further we sometimes apparently depend on rather recent icons.
So the only way to ensure Kube looks reasonable across the board is to make sure we always use the right icons, which we're going to do by shipping them ourselves into a kube prefix.
In the long run we may or may not allow altering the icons via the theme, for now it's one theme and therefore one iconset though.