I don't think there's anything wrong with a big or small approach to social networking, as both are necessary and useful in their own way. I think it's all about how well the site caters to their audience.

I used to feel that Facebook was just as necessary as Ravelry is to me (I am a knitter) until they started adding so much extra cruft and decided I want to read things like friends' comments on posts written by people I don't even know. So much extraneous information forced into my news feed and into the site in general made me stop using it as often. That doesn't even begin to address how anemic friends lists and such are for addressing how people really interact with the people they know.

In that way I'm really loving what I've experienced of Google+ so far. The idea of communicating in circles is so thoroughly baked into the product that it feels effortless to share one thing with, say, my coder friends, and something totally different to my family, without the other group needing to see that stuff.