Out of around 18 projects, in which we have used Mandrill, only in 1 we have used the template editor. (I think only about half went for paid accounts when the project went live.) Most of our need was simple and quick transactional messages (Registration, Forgot Password, etc.). The main reason we chose Mandrill was ease of set up over Amazon SES. (Even though we had AWS accounts for all projects.)

Anyways, it's up to Mandrill to choose who they want to serve. I really liked the service though. Best of Luck.