As for some of your specific points:
> Nobody is sitting there waiting for their news feed to update.
I check the feed in the morning and usually again in the afternoon. It's not expected to be something you stare at for eight hours a day.
> Nobody wants to seem like they are slacking off talking on social networks instead of working (even on the work one).
Think that's more of a company culture issue - our use of it is appreciated/encouraged.
> No memes and other fun related things, nobody cares and nobody checks.
The vast majority of posts are work-related but we have plenty of groups strictly for non-work/fun purposes (e.g. we have a group for discussing video games).