In the past it was not possible to trigger an automation rule when the only update made to an existing request was the update of the request’s template. This new trigger makes that possible.
Note that the template of a request is also considered updated the first time a template is applied to the request, i.e. when the request’s Template field gets a value for the first time. The new trigger also starts its automation rule after a template is applied to a new request and this new request is saved.