Triggers have lots of Actions, but those don't include the ability to add an Internal Note. In some instances, if a case meets certain conditions, adding an Internal Note (with pre-fab text like a macro) would be really helpful.
For example, if an Account Manager submits a case without the client on thread. An automated note could be posted to tell them to add the customer, instead of support manually sending a response.
An internal note could also remind the Agent of something (for example to timebox a case based on tier or to switch the Requester to the customer instead of internal contact).
Right now there is no way to automatically add a text string as part of a Trigger.