According to Twitter’s CEO Jack Dorsey, “One of the things we were watching for is to see if the if the average tweet size would go up as a result, and it has not. People do have the room — we’re seeing less abandonment of tweets. But we’re also seeing a lot more engagement. We’re also seeing more retweets, and we’re seeing a lot more mentions. And we’re also seeing people get more followers and return more often.”
This seems to be in line with a survey from last year, in which it found that users were somewhat divided over the new tweet lengths, where only less than half of those surveyed said that they liked the change. That being said, the latter part of Dorsey’s statement makes sense, because longer tweets do allow users to express themselves better, which in turn could lead to more engagement.
In any case we suppose the feature is there for users who want to take advantage of it, even though for now it seems that not many are.