In principle, Facebook is localised. I could imagine that few apps are translated to German though, and even fewer to Russian, except those built by native developers; (I don't use any apps, so I don't know) that native developer pool ought to be the same as the one building VK (or VZ) apps. Assuming Facebook does a decent job of filtering localised apps, I can't imagine this to be a massive issue for users.

I can only assume the media upload is what keeps people coming back.

All of the other reasons you mention seem to be reasons why businesses would prefer VK over Facebook, but surely it's the users that are the key?