I often get support requests or have to search for someone by their username (I use custom usernames).
It would be very helpful to have a column on the manage members page with their username. I'm also thinking this would be pretty easy for MM to add in.
Thank you for this suggestion! This feature request or some aspect of the functionality suggested is currently being reviewed for possible inclusion in a future update. If there is additional information, this post will be updated to reflect it.