MY guess then is that the people who are sending me email are not using the Mail app. I just went through 3 months of emails and only one of them had the senders actual email address listed. But that was because it was in the body of the email. The one I got that alerted me to your response was titled "Windows 8 Forums." But that isn't really an email address. I could, in most cases, reply back to the sender of an email without knowing their email address, but many times a person would like to add someone to their contact list, and you need a complete email address to be able to do that. I just can't find a way to do that with this new Windows 8 layout.
Update --- I just found out how to do it. You just have to hover the pointer over the listed name of the sender of the email, (in the email itself or in the list of emails that you have) and a window opens up and gives you the complete email address.