From the Minnesota Public Radio Replies:
"I'd want my parents, brother, sister, and my niece & nephew to know, too, so we could all come together with our extensive pet collections, drink wine (well, not the kids) and talk about how much we love each other." (emphasis mine)
Yeah. Wouldn't want your kids drinking an hour before the world ends. Imagine what it would do to their health...
Also some people seem to miss the point that knowing WOULD help people to survive, especially if they weren't directly at the impact site. If the thing hit in North Dakota, and you lived in New Hampshire? You'd still be seriously affected, but it'd make a huge difference whether you were in a tall building or a basement, or if you were standing outside at the time.
People should be told, so they can take whatever preventative (or therapeutic) measures they need to before the impact.