Facebook and Facebook owned Whatsapp happen to be so much popular that they're less likely to be considered as bloat if they come pre-installed on smartphones (which is the case with Samsung's Tizen smartphones such as the Z2, Z3 and Z4). The availability of Whatsapp in particular on the Tizen platform can be termed as a key factor for the impressive sale record of the Samsung's Z series of smartphones in its major markets such as India.
However, the UI and many features and services of facebook and whatsapp available on the big two- iOS and Android are still non existent despite multiple updates being pushed out on a regular basis. Another round of such update with a lot of bug fixes and internal changes is currently out now for Facebook and Whatsapp application for all Tizen smartphones including the most recent Tizen 3.0 based Samsung Z4. The latest update to Facebook now takes it to version 1.0.57 and WhatsApp 2.16.9.
You can find the updates in the Tizen Store by searching for 'Facebook' and 'Whatsapp'. We will keep you posted when there are any more updates in the future.