Email notifications are quite useful. However, I think that they would be even more useful if there were more types of events that can trigger the notifications.
Personally, I would like to be able to receive notifications when someone logs into my CF account or makes changes in my domains’ DNS records. These notifications would be a nice security precaution for me.
Feel free to propose more types of notification events that you think are useful. Hopefully, the CloudFlare team will implement some or all of them.