These days, most web based systems could replace login with email – although there is some problem there with emails changing and display names not.. I like the below system:

Old Name – Replaced with
“username” = “email address” (or “e-mail address”, never “e mail address”)
“password” = “pass phrase” (password is also a compound noun)
“login” as in the process = “Authentication”
“user id”/”nickname” = “Display Name”

But it confuses people so we stick with username, password and nickname etc.

In a business world, fitting with other apps is often more important than good grammar. If a customer wants to “login” not “authenticate” then that’s what they get. If a user wants “primary securing identity key” I’m sure they’d get that too.