Twitter users tend to be under the impression that everyone is on Twitter.
Depending on who you follow, it's one of the best link aggregation sites around. Care deeply about refugee rights in Myanmar? Follow a few folks and you'll gain insight into the kinds of things like-minded folks are thinking about. There is the on-Twitter conversation, too, but the best thing about the site is what people are linking to out of it.
Sure, I'm a Twitter user too, just pointing out the tendency of people to forget that there's a world outside their own, especially if they spend enough time in their own little curated space on a site structured like Twitter.
Twitter has always seemed to be of very minimal utility to me compared to other social media. It basically takes the vacuous shouting into the void of Facebooks wall, and makes it the only feature. I'm kind of not surprised that people don't use it.