Besides using kubectl to manage VMs, you also get VMs that join the cluster network as first-class citizens. In this blog post you can see a k8s service pointing to a VM and accessing k8s services from within the VMs. Also, compared to EC2 / GCE / etc., you can use Virtlet for bare metal on-prem clusters, too.
Also, how does a Kubernetes-managed VM compare to a plain VM from, say, AWS EC2? I imagine it's a little less efficient, since the situation I'm imagining involves various VMs running a Kubernetes pod running the VM, but I may have this all wrong.