I ask for two reasons. First of all many users do not respond to the Closed message and instead reply to the survey. Being able to put the request ID in the subject would allow these replies to reopen a request instead of generating a new one. Secondly users would like to see the description of the request when they open the survey email. This way they can give proper responses to requests where they receive good/bad service without needing to click the survey link and find out the email was actually for the password reset the called about and took two seconds.