I don't think that's the only way. Imagine if i want to have multiple isolated memchached instances running(i can hardly imagine when would you want something like that, but let's say that someone wants). It becomes confusing for someone when users are created only for first instance. I think it's better to have an option to specify if you want to create a user, or just leave everything alone. You can always set users.extraUsers.memchached.createUser to false and user won't be created on a system and get rid of additional unecessary complexity.