If Google just wanted me to add a few relevant details to my primary account for some obvious useful purpose, details that would be kept private, I would happily oblige. However, this goes beyond that: Google is asking me to share information with no apparent application use (birth date?! gender???) to ANYONE who stumbles upon my G+ profile. I am not against unifying their services - in fact, this is what Google's basic authentication service should and could have done - but that is not the full extent of what is happening here, as far as I can tell.