Apologies for the late response. One of the reason we didn't provide reason in the header is because the reason will is more descriptive in some cases and can occupy lots of space.
We do give the reason for the alert in bold at the beginning. I guess thats not eye catchy... We understand the importance of it.
On another note, we will be working on giving customization options for the alert email so that customers like you can modify based on your requirement. But the feature is still in discussion stage.