Figured that was just about showing a class divide. Rich people's names mattered, there was no point in calling him Sokka Fisher. But most anyone would want to know her family, so they needed a family name. Then when a name becomes prominent enough that people think it is more important than your individuality they put it in front of your name. Avatar Roku, Admiral Zhao. I suppose it is just a role more than a name, but in practice Lt. is all they care about... The name following it is just the tool stuck performing the job.
In feudal societies, often only the wealthy needed last names. If you were a serf, it didn't matter what family you came from. Last names (for commoners) only became a standard thing in Europe under Napoleon. I'm not sure about the history of Asian family names.
And it was often literally the wealthy, not nobility. When the feudal system started showing cracks in the renaissance and merchant families became de facto rulers of their cities, those families started taking surnames, which eventually spread to the rest of the commoners. Nobles kept the 'X, house of Y' format, but most never made the leap to true surnames.
My anecdotal understanding is that Chinese surnames are ancient, being commonly used by the masses in times before the Caesars ruled Rome. In the earliest days there were only surnames for noble families but they became pretty commonplace very quickly. My own surname denotes an ethnic group, but others may be professions, titles, or regional identifiers.
IIRC, Japanese surnames are more recent, with only clan names of prestigious families in use prior to the 1800's (e.g. Taira no Kiyomori, Kiyomori of the Taira). When Japan westernized and mandated that people adopt surnames, the majority ended up being some kind of geographical/positional/professional descriptor. A common Japanese name, Tanaka 田中, is made of the Chinese characters for "field" and "middle", so it roughly means "in the field" and indicates someone who was probably descended from a farmer. Another common name, Yamashita 山下, is made of the Chinese characters for "mountain" and "below" and indicates someone whose ancestors probably lived at the foot of a mountain.
I know nothing about Korean names since they aren't written in Hanzi, but I know they used to be, so it wouldn't surprise me if it was a similar situation. I likewise can't speak to other countries in central Asia or SEA.