I suspect facebook never became a place to meet people because the user interface, hints, and tools were designed to focus on connecting you with the communities and people you knew. That mentality stuck even as the network grew up. When G+ launched, networks for meeting strange people had already established (e.g. LinkedIn), and one of the big questions general users were facing is how to manage different groups of people (personal friends, colleagues, virtual discussion buddies, etc) in a single network. That set a different set of exploratory goals which early adopters tried to achieve, which contributes to the difference in percieved value.
I'm not a Google insider, so I can't claim to know what Google is planning with G+. But from what I do see, they have plans that go beyond 'being social' or 'beating facebook' – they seem to want to monetize by integrating G+ into search results. That means the nature of their interest is helping people find other people, in particular not just people they already know but also experts who they do not yet know and how and where to get in touch with them. That's a different focus than facebook's vision of bringing the world together. And that the clarity, or lack thereof, in the two visions reflects itself in the design and functionality of the two platforms.
Note: I'm not saying that G+ is good or Facebook is bad. I do think that both networks have their good and bad features – there are also features that work on Facebook much better than on G+, such as forum-like topical discussions. But I am saying that for purposes of discovering new people with similar interests, G+ is more successful, and that there's a directed reason for it's success.