Joey D’Antoni argues in favor of automating SQL Server installations:
Anyway, on to my original topic—I know most shops aren’t Comcast where we were deploying multiple servers a week. However, automating your installation process has a lot of other benefits—you don’t have to worry about misconfigurations, unless you put in into your script. It also forces you into adopting a standard drive letter approach to all of your servers. So when something breaks, you know exactly where to go. And more importantly you save 15 minutes of clicking next.
For any shop which deploys SQL Server more than a couple times every few years, automating your installation process is a smart move. Even if you rarely deploy, the consistency benefits make it worthwhile.