A great use case for this is the possibility of you customize a script the value of the severity of the triggers for each type of item or alarm. This script generates the output in JSON and can be easily used in templates that use the LLD feature.
In this post (in Portuguese) there is a script and a real scenario that uses all. The only thing that can not automate is precisely the severity of the triggers.
In this post, it is simulated a web application that manages events to be read by a script that generates the output in JSON to be monitored by Zabbix.