If you think it is still an option to have a +Google account but not a #G+ account... you might soon get frustrated. 
At https://developers.google.com/events/io/sessions/331521903 you'll see that Google wants people to start using G+ auth instead of the previous Google auth, and they're just assuming that if you're a Google user you're a G+ user. 
Not that I'm surprised or even disagree, but I've seen a handful of people lately either removing their G+ account or telling me they don't want one...