Facebook apps don't do anything "useful" - so what?
Here's the chart:
Now, first off, let me come out and say that I love making fun of Facebook. I avoid using it whenever possible though I still keep my profile around in case, one day, it might be useful, even if only as a rolodex.
I do not, however, see any problem whatsoever that the vast majority of these apps are in the 'Just for Fun' category. In fact, I can't really imagine a situation where that wouldn't be the case.
People get tired of being asked to be zombies or whatever the latest app is over and over again, but it's still increasing communication and practically throwing social utility at you.
Social utility is a term I thought I had just made up, but a quick Google search shows that not only am I not as clever as I had hoped I was, but that's exactly the term that Zuckerberg used to describe the app environment.
Facebook is about communicating with people and they (unfortunately) do a pretty good job with it. It definitely has lots of major flaws, but dissing the system based on this graph is just muck raking.