A long piece in the Wall Street Journal on Google+ is pretty damning. The case against: it’s a “ghost town,” with 90 million users who don’t spend much time there, it isn’t differentiated from Facebook enough, Zynga says it’s disappointing and marketers like Intel and media buying agency Universal McCann agree. Google’s Bradley Horowitz, VP of product management, says that Google+ is not just a destination, but a social integration strategy across Google products. That’s something I’ve been pointing out since day one, even though that integration has drawn fire. In fact, I’ve even said it’s not important for Google+ to succeed as a destination, based on Google’s strengths in search and email. But I’m beginning to change my tune. Google has the potential to bring along traffic and a ready revenue stream for developers, but not if it doesn’t connect its ad networks, and if those apps never get discovered or used. Facebook still lacks an effective apps marketplace, but Google has yet to exploit that.