I'm not kneejerk about the privacy thing, I'm not for (in the abstract) personal privacy. What bothers me is that their approach stifles creativity and, as Pete says, goes against the culture of the internet.
The idea of having an identity rank isn't bad in itself, it could be useful and helpful. It's the fact that they want to profit from it and that there are sinister organisations who will put it to sinister uses. If the information they harvest was genuinely public that would be great.
I guess the thing to do is just make a gmail account from scratch, not tied to anything else at all, use a false (but realistic) name and use that to sign up for G+.