It may be true that FB is making more use of the data than you might have anticipated, but you can argue that's also the risk you take when you use a free service (do you ever really know the full extent a service will use your information, despite what they say in their lengthy EULA?). The funny thing is that in many cases, the user gains more value from the system than originally expected too, due to novel applications of existing data (e.g. timeline).