The long-term strategy of Google+ has not always been clear to everybody. It’s not a social network to replace all networks, but a way to add meaning and context to how people use Google services. Whether it’s search, maps, Now, or anything else. Slowly, but surely, Google+ invades all facets of Google. To think it’s come this far, and all without any kind of usable Developer API, is quite sobering. Already, G+ drives a large amount of traffic to sites, but he flood gates are yet to open.
On a related note, social networks use for shared logins on sites. Something that I strongly discourage. Spend a few minutes and create a login with a randomly generated password, with no link to your social profile.
“After Page Authority, a URL’s number of Google +1s is more highly correlated with search rankings than any other factor. In fact, the correlation of Google +1s beat out other well known metrics including linking root domains, Facebook shares, and even keyword usage.”