I've never thought the 140 or 280 character limitation added much value to Twitter, and the ubiquity of multi-post Twitter threads seems to be evidence of that. And the price we bad for such brevity - lack of depth, focus on the quick comeback, etc. - seems not to offset any good the form produces. But what the shift really signifies is Twitter's long overdue recognition that it has transition from being a messaging service to being a publishing service. After all, you don't get much traction offering political candidates a messaging platform. But - also - to my mind none of this matters unless Twitter opens its API to the point that users can join the wider community of commentators, doing more than just talking among themselves.