One compelling reason for an SMB to use Google Plus was the fact that their most recent G+ posts and photo would appear on the Knowledge Panel for branded search results. First noticed disappearing by Mary Bowling about a month ago, it is now gone for good.
Google confirmed its passage by saying: “We’re always mixing things up on Search, and this change is no different. We’ve found that most people care about seeing hours of operation, directions, and photos when they search for businesses, so we’re making that information the most visible. You can still find all this info in Google+ of course.”
Here is a previous knowledge panel showing a G+ post and image and a current view showing its absence:
Google+ Knowledge Panel Messaging Gone by Mike Blumenthal