"Also ran social network?" It's been running for how long? Second only to facebook and isn't a neverending class reunion? SIGN ME UP.
Only days before this functionality was announced, I and my writer friends were bemoaning the fact that you can't email people you 'know' quite well through G+. Now you can. I'm happy.
By all means, of course, control the access others have to you, but Doctorow's lack of perspective is disappointing.
Less poisoned-well post from cnet: http://news.cnet.com/8301-1023_3-57617033-93/how-to-prevent-google-users-from-e-mailing-you/?part=rss&subj=news&tag=title