I would also point out that comment by Richards is dated 2009, so responding as if the poster was still active in the thread may be off-base.
Beyond that, however, if you do have expertise in the area, and want to see the game become a culture simulator, then could you supply us with the sorts of guidelines for which different naming conventions actually arise?
In that way, we might be able to make this something more than just a hard weighted chance of one or the other, and we could actually have that simulation of culture changing with time in the game, and make them procedural changes that emerge through gameplay.
Ahh, when I normally do that kind of response I pay attention to the date of the other person's post (and at least make mention if it is fairly old). To emphasize why I responded well . . . here's an xkcd comic to explain:
http://xkcd.com/386/ (and I am poking fun at myself). Also, I'd like to apologize if my response sounded at all harsh.
As for my expertise: it is extremely limited. I am familiar with the fact that there exist other naming systems that reckon from mother side, father side, and mother and father side along with all kinds of other weird and different stuff. For instance, in one system an individual doesn't actually carry a name. Instead they acquire names by their relation to other individuals. IE I might be known as Joe by one person or one group of people, but by George by someone else (kind of like nicknames, but not quite). At least, that's how I understand it. Caused havoc with the census that they tried to do in Papua New Guinea. People actually had to invent personal names JUST for the census. Which, admittedly this system might be fun in DF (imagine the description and relationship pages).
Really, when we get into the nitty gritty of this it probably would be worth discussing kinship terminology and systems, property, labor, and marriage (monogamy, polyandry, polygyny, different rules of marriage, etc). These are all interconnected to an extent so while we might not take a stab at what causes what (correlation does not equal causation) we can say what correlates with what. So Toady might still want to go by hard rules, just have generated cultures to have systems that make 'sense.' The hard rules will just a be bit more educated and we can sort it all out later with diffusion and maybe some other system. Ultimately, though, we're dealing with dwarves, not humans, so we can say they follow whatever rules might make sense to dwarves. They might name based off of beard length of parents (which right now would favor a patrilineal system) or something that makes a little bit more sense, but still wouldn't fly with most humans. It is hard to think of an example, because humans do all kinds of weird and awesome things when you get down to it.
I don't know how in depth I'll discuss this. I can probably write a
book just off what I've mentioned so far (if not a whole series) so what I might do is pick out some exceptional groups that seem to 'represent' a way of looking at naming and list cultural 'traits' (ie kind of kinship system) even though I dislike going about it that way. I can always expand on the traits if it seems like a good idea. For examples of patrilineal and matrilineal systems I can look at America and the Iroqouis (or the Hopi). I'll probably look at the group from Papua New Guinea along with Tibet, Turkey, and India to see if we find anything interesting that might fit in DF or just seems cool.
Edit: I'm listing Tibet, Turkey, and India because I suspect they might have some weird awesome naming systems. Spain differs from the rest of Europe in its naming, so I suspect they may have picked that up from the Ottoman empire (which had a hand in Spain for a very long time). Turkey is what is the left of the Ottoman empire which is why I'm looking at them. Meanwhile, Tibet actually practices polyandry last I heard so I'm interested in how they reckon lineage. Meanwhile, I've always been interested in India. They seem to practice a different naming convention, but I've never really found out what they do specifically.
Let me know if you guys think of anywhere else you want me to take a look at while I'm at it!