This would be extremely helpful. To echo the original poster’s point, the user building the email could forget to manually choose the list needed in the ‘Do Not Send to’ field. Having exclusion lists be pre-populated in designated templates would significantly reduce the chances of human error.
Mistakes like this prevent us from being able to send as many emails as we would like, and thus reducing our overall engagement with HubSpot. If we had this functionality, we would definitely be utilizing HubSpot more.