The motivation is more the latter, but it's not at all clear the proposed removal of the embedded kustomize will proceed, given the compatibility implications. See discussion at https://github.com/kubernetes/enhancements/issues/4706#issue... and following.
> proxy.golang.org does not save all modules forever. There are a number of reasons for this, but one reason is if proxy.golang.org is not able to detect a suitable license.
If you're vendoring something without an appropriate license, you're skating on thin ice legally.
That's just one possible reason. The disclaimer does not specify all the possible reasons the proxy would drop a saved version. Treating it more like a cache seems appropriate.
If you decide to run with the RBAC authorizer, tools like kubeadm run the control plane components with credentials that have the required permissions out of the box. If you're using your own deployment/setup, you'll want to consult https://kubernetes.io/docs/admin/authorization/rbac/#core-co... to either give standard user/group names to your components, or grant the appropriate roles to custom user/group names.
Once your control plane is running, granting API access to other apps that need it is typically a matter of creating a service account, setting that service account in the pod spec, and granting the service account a role with sufficient access. See https://kubernetes.io/docs/admin/authorization/rbac/#service...