Good questions!
We have a 3 Tier organization as follows...
NOC - Tier 1
Admins - Tier 2
Engineers Tier 3
Our NOC would watch the AC console and their user accounts would be set for no email. If they saw an issue that needed to be escalated they could use the console to escalate the issue to an Admin (Tier 2) whose user accounts would be set for email.
Basically having the ability to turn email escalation on/off at a user level would satisfy the NOC use case as well as the original design and use cases of AC.
Thoughts?