Facebook already has a data export feature. You have to manually navigate to that page and download a giant zip file. Cool.
The much more important concept being proposed here is delegation:
> Under the bill the companies would be required to maintain an interface to facilitate interoperability. Or users would be allowed to choose another company to manage a user’s account settings, content, and online interactions, the statement said.
Very few people are going to manually export their data from Facebook. But they might go to a new network that supports cross-posting to Facebook, or an automatic import that doesn't require them to navigate Facebook's menus.
Delegation is a severely underappreciated digital right. Beyond advocating for data-exports, we should advocate that users have the right to delegate data-access through APIs to third-parties. If I can manually update/download my Facebook status, I should also be allowed to programmatically update it. And I should be able to authorize another person to update/download it on my behalf.