
If was to change a user account login name only, the most significant issue is the ticket LOG, where it stored the username, not the user_id. So if the user was
ABCuser for the past year.
You change the user to
XYZguy today.
All past tickets log still show "ABCuser", new ticket logs will say "XYZguy".
A year from now, someone needs to audit that ticket. Who is "ABCuser" ?