I'm not going to argue here about whether Twitter's character limit produces better or worse discourse by any particular metric. My only point in the comment above was that the character limit remains a fundamental characteristic of Twitter, and removing that constraint would qualitatively change Twitter, in a way that "emoji now always count as 2" and "we're moving from 140 to 280 characters" did not.

Constraints can lead people to be more innovative and creative. That does not mean they universally do, only that they can. Removing such constraints is thus not an obvious improvement with zero potential downside.