Normally the toolhead should never hit any object. If it does, and the cover detaches, it can be detected and the printer stopped before any significant damage is caused. Fallen off cover > broken machine.
The cover needs to be detachable to change or replace the hotend, and you need to have the cover for basic protection and better airflow control (I assume), and it’s best practice to have a sensor to protect from user error. If the sensor is already there, why not also use it during the print?
Normally the toolhead should never hit any object. If it does, and the cover detaches, it can be detected and the printer stopped before any significant damage is caused. Fallen off cover > broken machine.
The cover needs to be detachable to change or replace the hotend, and you need to have the cover for basic protection and better airflow control (I assume), and it’s best practice to have a sensor to protect from user error. If the sensor is already there, why not also use it during the print?