Add additional Status values
It seems the current list of Active, Onboarding, Unsubscribed, Bounce and Transactional are not sufficient for our needs. We would like to know they reported an email as 'Spam', were unsubscribed due to a 'Hard Bounce'. We would also like a status that can be set from within a workflow that makes the contact 'Inactive'. This would allow us to inactivate contacts based on our own criteria and keep them out of promotional emails but keep them on the file. They can be made active by a form or API or even workflows. They would still be able to unsubscribe from emails from the account page on our site but we can tell the difference between contacts that have unsubscribed and contacts that we chose to make inactive.
About the inactive part: Would an exclusion list do what you want? They'd still be subscribed and on the lists they chose but they'd be (invisibly) excluded from message deliveries.