There are a lot of things users of Twitter have broadly requested over the years in hopes that it would enhance the experience. In 2017, we have not only received the ability to author longer tweets, up to 280 characters now, from the original 140 characters, but it seems like the service is going to allow users to update their display names with more characters as well.
Starting today, those that want to have a little fun, or maybe that just want to perhaps add a middle name, will be able to do so, as long as it's up to or less than 50 characters in length, up from the original limit of 20. Now, this doesn't mean you'll be able to create a longer username, which is different. A username is what's used to log in to the service and what shows up in the address bar in the browser as your unique identifier. A display name is what shows up on your profile and is what can now be lengthened and even customized with emoji.
Sure, this might not be the enhancement you were hoping for, but at least you'll have something fun to toy with until a universally requested feature arrives on the platform.