Skype usernames are on the way back, according to a Skype forum. Skype Community Manager, Petr, states that Microsoft is still working on bringing back usernames to Skype in a Skype forum. Petr responded to a piece of feedback from December 2018, so the feature has been in progress for a while.
Petr states that there are “many blockers for [the Skype team], both technical and legal but it is in progress.”
Skype usernames may be seen by some as an odd addition, considering that Skype has a large base of professional users and usernames are often used casually, but one comment points out that usernames allow you to keep the same account without showing a silly email address that you used as a kid.