That is right, if you want to keep using the kickstart script method to deploy an ESXi server.
But since vSphere 5 the AutoDeployment was introduced. See vSphere 5.1 – Auto Deploy Stateless Caching and Stateful Installs for some info.
Check out how such an autodeploy works in this HoL called HOL-INF-03-m1 and more importantly, how you can script this from PowerCLI