[kmavm]

I'll let Google explain the exact same product decision for their social network Orkut in 2009:

"Mass exportation of email is not standard on most social networks — when a user friends someone they don’t then expect that person to be easily able to send that contact information to a third party along with hundreds of other addresses with just one click. In order to protect user privacy, we now exclude email addresses from the CSV export file."

http://techcrunch.com/2009/10/26/orkut-slows-hemorraging-to-...

They're right. Programmatic export of friends' email addresses is too ripe for abuse in the world we live in.