Hey there,
The reason that we implement user id instead of username is because of the security reason.
If the username is known by opening the image in the new tab, they can know your username and they just guess your username's password as shown in the screenshot. The account will be easy to be hacked.
If you really want store it as username instead of user id, it requires for customization to do this. You can always request for a quote from us at
https://crm.stackideas.com and select "Customizations". Our sales person would be glad to send you a quote for the customizations that you have requested.