It would be great if there was a way for a specific list (smart or static) to always appear as 'Excluded' on all email send-outs, as a default. While in most cases we would like to retain this list as excluded, the user could still manually choose to remove the list from the 'Excluded' field.
As far as I am aware, currently Exclude lists (like Include lists) must be added by the user at the time of send. There's no feature to add this list automatically.
While I understand that the reason behind this is to give the user the most control over their send, but in certain cases it'd be useful to have this feature to prevent from unintended email send cross-over or from targetting certain audience groups.