In fairness, Facebook did the same thing.
Google does so many things for many different people. Opening it up to the world outright is technically dangerous, but Facebook had a very natural progression for rolling out because they had identified and located their market. Google isn't so lucky. + is designed at the Facebook user base, but isnt considering the history or the trajectory of Facebook users.
I'd imagine the only reason google cares about social at all is because it is a significant source of revenue in an industry they want to own (advertising).
All that said I'm going to set up an account when it's my turn.
Otherwise, it's really not the same thing at all.