Facebook has 2.85 billion users workdwide. Clearly they are not as concerned as yourself.
I don't really understand why you find "What's on your mind?" sinister. Seems like a perfectly reasonable question to me.
I've been a member for 14 years, ever since my 2 daughters emcouraged me to join. Since then, I have been reunited with two schoolfriends, one from Primary school and one from senior school. I have also, randomly, made friends with people in Canada, India and Australia. None of that would have happened without FB.
Like all social media (and indeed "things internet") it has its negatives (what in life doesn't), but it has many positives too.