Valid point, but the hurdle associated with exporting and re-uploading that data is non-trivial for most people. Is it truly portable if a user can't figure out how to take it with them in the first place?

Edit: I should add that I think a fairer exchange of information between Google and Facebook would be a good thing for users. I just think the way Google is doing this conflicts to some degree with their past mission statements regarding users owning their data.