I think Google+ could be understood better once you realize that Google+ is not a social network in the traditional terms. Google+ is truly a social layer across all Google services.
The average users who are just looking for a chicken recipe (as you mention) would always love to find the particular chicken recipe that their friends have recommended. Even more relevant to me (since I don't cook) is that if a friend finds a todo app useful, I'd definitely want to know.
If Google has this social layer, it'll really unleash more expressive search results that would help the vast majority of users. This is what Google+ is.
Google+ is literally Google Plus More.
Of course, to get these benefits you really have to start using Google+ on different Google services. I guess this is the reason that Google employees who actually use Google+ services continue using it and prefer if their friends do it too.