You are correct, system databases are every bit as important. But in my environment they do not require as aggressive a backup schedule. So i basically run 2 versions. ! for User databases and a second for System database.
If you feel very adventurous you could create a table that stores the databases on your system and add meta data to determine when and what type of backup to run. But then the table has to be maintained. So we turn the wheel and start over again. 🙂
Please feel free to use this as a jumping off point for your own backup strategies.