グーグルプロフィールの姓名が公開される方針

　いろいろなサービスがありすぎて、ある意味mixiなどの役割まで兼ね始めているようなところがあるので、防犯上、ということでしょうか。ただ、ニックネームのような姓名を使っているひとはいくらでもあるし、携帯電話アドレスで一意に定まるユーザー登録や、郵便番号や住所の登録までしないのであまり大差ないようにも思いますが。

Profiles › Help articles › Profiles › Profiles overview › Public profiles
Profiles overview: Public profiles

The purpose of Google Profiles is to enable you to manage your online identity. Today, nearly all Google Profiles are public. We believe that using Google Profiles to help people find and connect with you online is how the product is best used. Private profiles don't allow this, so we have decided to require all profiles to be public.

Keep in mind that your full name is the only required information that will be displayed on your profile; you'll be able to edit or remove any other information that you don't want to share.

If you currently have a private profile but you do not wish to make your profile public, you can delete your profile. Or, you can simply do nothing. All private profiles will deleted after July 31, 2011.
http://www.google.com/support/profiles/bin/answer.py?hl=en&answer=1192471&p=public_profile