I think some of the issues around this come down to the way we conceive of these networks (well, and semantics.) They're all called Social Networks, but that should phrase be construed very broadly. If people are using Facebook to keep in touch with a small circle, Twitter to a broad audience, and G+ as an RSS reader with pictures and a +1 button, then they aren't the same thing at all. Feet, bikes, and cars are all kinds of transportation, but they're thought of differently. We don't talk about the failures of feet because people don't walk enough. It's how and why these things are being used that defines what they are.

Perhaps if Google embraced (and re-branded) itself as a content network/social content network/RSS reader with glowing bells things would be understood (and talked about) differently.