In my current work, we run several Kubernetes clusters via GKE on Google Cloud Platform. We're a tiny company — less than 20 nodes running web apps, microservices and search engines — but we're benefiting hugely from the operational simplicity of Kubernetes. Much, much, much better than the old fleet of Puppet-managed VMs we used to run. Having surveyed the competition (Docker Swarm, Mesos/Marathon, Rancher, Nomad, LXD, etc.), I'm also confident that Kubernetes was the right choice.
Kubernetes may be a large and complex project, but the problem it solves is also complex. Its higher-level cluster primitives are vastly better adapted to modern operations than the "simple" Unix model of daemons and SSH and what not. The attraction isn't just the encapsulation that comes with containers, but the platform that virtualizes physical nodes and allows containers to be treated as ephemeral workloads, along with supporting primitives like persistent volumes, services, ingresses and secrets, and declarative rules like horizontal autoscalers and disruption budgets. Given this platform, you have a "serverless"-like magically scaling machine full of tools at your fingertips. You don't need a huge workload to benefit from that.
As for LXD and the other alternatives, these might be great, but Kubernetes has vastly more mainstream adoption these days. That's more important than mere technological superiority, or everyone would be using OpenSolaris with Zones and ZFS these days.