I'm not sure if you're being sarcastic, but these are of immense historical importance. Often times the big historical events are only seen as such in retrospect. So people's reactions to them tend to be heavily based on conjecture and memory rather than solid data. Say what you want about twitter, but it serves as a minute by minute log of the emotional state of people within seconds of anything happening. And yes, there is some selection bias going on in that it's only data from the kind of person who uses twitter. But that's still a million times better than the couple articles by newspaper writers looking for a story, and who'd probably not be interviewing the common man on the street for what seemed like a blurb at the time. The short answer though is that it's not for you and me. It's for the generations not yet born.