Username is still used in Server reporting and on most installs will still be the default.
Either a scripted action or additional dialog when a user enters their account name and password on opening a file.
Something like SetUsernamePreference(Get(Accountname)) or another check box to set the account name as the username in the log in window. Or ask if they are saving the log in credentials to set the username.
For users it is an extra step to go into preferences and set it themselves, especially if they are used to saving credentials they rarely see the default "admin" but as it's part of server logs it makes for extra work reading logs to figure out which of the multiple "admin" usernames is the one you want.