It's not, it's meant for cases where people need entirely different custom hostnames. Subdomains are quick and easy, but people have become quite a bit more demanding about how their stuff is branded, and tend to want it all on mydomain.com (instead of me.service.com).

Actually I lied, it's probably a little easier than a wildcard cert. :D But not enough to matter. People who just need wildcard subdomains might want to use us for other reasons. We handle all load balancing, global SSL termination, etc. These things are stuff you'd use even if you were just using a wildcard cert.