Nobility has always had family names though and the common man has generally emulated them. And while I'm a Scandinavian with the surname Petersen (son of Peter) there are also people called Møller (Miller), Jæger (Hunter), Bonde (Farmer) and Rex (latin for king, illegal for anyone but our royal house to have as surname.) I think UO designers may have simply made a conscious choice to make Britannia seem less formal. Or maybe a subconscious choice. Also, guildstones didn't exist in the early retail stages of the game, but plenty of people were in guilds before they even started, so they used their guildname as a surname and habits tend to stick. I would still start my characters in the North Side Inn if I still got to choose which inn to start characters at.
You don't get a last name until you reach level 20. Last names can hold a lot of meaning. *shameless plug for thread in the salty dog saloon*
My family heritage traces back to Greece and so I have used a blended method of naming orthodoxy to blend that heritage into my gaming. So my main name I use in many gaming settings is Mykos. My name being Mike and with a little altering of letters and adding an -os to the end, I get Mykos. It is usually shortened to Myk, which works since my name is Mike. Other characters names are transaltions of greek words, depending on their skill sets. Tekton and Charash are examples of crafters. Only one of my toons has a surname and I am not quite sure why I chose the name I did other than I liked the sound of it. All other characters are single name only.
Wry-nosed, Wry-mouthed, Son of Ugly. Buck thighed, High toed, Crooked arsed, Braggart, From a small island You have lovely names. (Don't get me wrong here, there are far more poetic names. Yet those ones should be worn with pride)
The colorful words of Pfniffel, Soever worth much more than a nickle, Worth more than a dime, Compounding interest with time, The freedom of Franz did down trickle. - Lion
Yeah but they don't have had "last names" wich are taken from their professional like it was in central europe this time (miller, hunter and so on) and mostly the scandinavians had either nicknames like those you posted or their lastnames were taken from their fathers names and ended with whatever they were to him (son/daughter) like halfdansSON / halfdansDOTTIR. Best example today are islandic names, they almost didnt changed over the past centuries. And most of the times they've got their nicknames from others outside their families.
I feel like such a chump that, despite all my table top RPG and love of characters, I've always stuck with the name 'Aragorn' in mmos, which I picked in UO beta as a teenager. I just can't seem to break away. I make other characters, but they just feel wrong most of the time.