What's open about Google+? You can delete your account and download your data from Facebook as well; you can also write third party applications that read and write from/to Facebook, unlike Google+.
"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.