Help provide production support when users can't submit shopping carts and triage exactly what that user is experiencing. They would require the ability to order on behalf of a Customer and to View Orders within the security context of the user. In addition we have other use cases that would allow users to login on behalf of an Approver for Approval or Orders.
All of our needs can be met by allowing subset of users an ability to impersonate. However, this option wouldn't work if we can't constrain what the Administrator privilege is able to access.