Why not just re-enable last names for new Avatar Accounts?

[Alyona Su]

6 hours ago, Kimmi Zehetbauer said:

And some in world get mad if you call them by the system name. I did that when the display name was a bunch of characters I couldn't make out, especially with my ancient eyeballs!

Just precede their user name with "the one formerly known as [username]" I do it all the time. You you could just say you have display names turned off, just as so many have voice turned off.