The problem begins to become more nuanced when you go further back in history - not just with other cultures.
Choose a profile from medieval or renaissance royalty at random, and ask yourself if the profile really represents the birth name. I picked
http://www.geni.com/profile/edit_basics/6000000007442241030
Was he really born Henry VIII Tudor, King of England?
No, he was born Prince Henry of England & France. Royalty didn't use surnames. His father was born a Tudor, but he was not. Calling him Henry Tudor, VIII wouldn't be right either - he wasn't the 8th Henry Tudor, even we somehow imagine he was a Tudor. The VIII was never part of his birth name. He got that when he became king.
We call him Henry VIII, King of England because we know him by that name. We insert Tudor, because we like people to have last names, even if they didn't. We leave out France because he didn't really rule France (except Calais). And, we use the VIII instead of II, because we don't really care that his father was also named Henry; we only care that he was 8th Henry in the list of kings of England.
That's taking a lot of liberties. I think some of my fellow curators would argue that we should go back and change all those royal and noble profiles to their real birth names. And, while we're at it, if our earliest record is a baptism record written in Latin maybe we should change those birth names to Latin, and stop translating them into English, French, etc. ;)
My point is that the standard isn't as clear-cut as we sometimes think it is. We sometimes make compromises in our work so that it becomes understandable. Most of us understand perfectly that it is better to call people by the name we know them by if we want other people to undersand. The folks in academia, as well as the folks in Hollywood, know this - they write papers and make movies about Henry VIII, not about Prince Henry of England and France ;)