Not to excuse this in any way, but that sort of sky bump is a rare event, which is why you can find a news story about it. And, also per that story, people can end up getting hurt in those circumstances even though they're seated.
Again, we don't have standing room planes for very good reasons. And breakdowns in safety protocols should be worrying. But as a one-off event, the incremental danger is actually pretty slight.
Otherwise, totally agree: compared to total number of flights (there's maybe 1000 B737 and A320 in the air at any moment), rare (though potential consequences could be grave.)
And, as you say, it's the negligence of basic safety protocol that's worrying.
An Air Canada flight in 2015 had 21 people injured, including a broken pelvis.
http://www.cbc.ca/news/canada/calgary/tsb-investigation-air-...