The problem with data portability is that it goes both ways: if you can take your data out of Facebook to other applications, you can do the same thing in the other direction. The question, then, is which entity is likely to have the greater center of gravity with regards to data: Facebook, with its social network, or practically anything else?
Remember the conditions that led to Facebook’s rise in the first place: the company was able to circumvent Google, go directly to users, and build a walled garden of data that the search company couldn’t touch. Partnering or interoperating with companies below the Bill Gates Line, particularly aggregators, is simply an invitation to be intermediated. To demand that governments enforce exactly that would be a massive mistake that only helps Facebook.