They're all terrible. You're a human being with dignity and a name, not a farm animal. Any employer who tries to name you as the latter should be politely asked to stop.
I think they're a lot more natural than you make it sound. I mean we have denonyms from placenames. Some of them are fairly rote (newyorker, londoner, dubliner), some take some imagination (okie, mackem, geordie).
I really don't see why this is any different?