Have you created a Moment? The format is very similar (a screenful of content), save from the disappearing part. But Moments don’t propagate or get distribution like tweets (the creator must tweet a link to one), so they lack automatic distribution and engagement.
Twitter also seems to be less about capturing your life as it’s happening and more about participating in a global, public conversation or adding your commentary to what’s happening in the world. Stories, in contrast, tend to be more personal and about an individual’s unique experience. How would you square the public nature of Twitter with the way people tend to use Stories elsewhere?