I think the knowledge skills could also serve to define the knowledgeability of a society. And this could, for starters, be based on the Intelligence (or other scores) of the society's inhabitants.
Human intelligence, assuming you use 3d6, is an average of 10.5, which we could treat as meaning the maximum number of knowledge points a human can accumulate in any one discipline is 105. In addition, I also note that we could round 10.5 down to ten so that human character scores can go up to 100, a nice round number. I've been treating 100 as the maximum number for my knowledge skills, so maybe I'm biased, but it's nice to have a maximum number is easily understandable by everyone while still having lots of room for fiddliness.
Of course there may be techniques beyond the human racial limit. And furthermore I suggest the limit be based on the average of human intelligence, and not be subject to decrease or increase based on individual character intelligence.
In this case, then I believe that technological and industrial knowledge, in the "Civilization" videogame sense, should definitely be included as types of knowledge ... or, from a different perspective, I believe that the character knowledge skills should fit into and draw from a wider cultural framework. Not just adventuring-type stuff, although some things can be just about that. I'm talking things like pottery, weaving, combined arms attacks, civics, bureaucracy: material, political, and cultural "technologies," i.e. types of knowledge.
This implies that the knowledge skills are accessible to NPCs, which I have already been doing. That's where the "sage skill" concept comes from, after all: the idea that some NPCs have expert knowledge. Knowledge skills as they work now are just granting that knowledge to the player characters, too.
Now let's look at a non-human society.
Suppose the book lists goblin intelligence as 6. Taking that 6 as an average (a die roll of 2d5), then we determine that goblin cultural practices (and the knowledge skills of individual goblins) can't go past 60 points (again, per-discipline.)
If we have skills for theology which actually reveals true facts about the fantasy game world, for the burial of the dead to prevent their rising or to have them go to heaven, for the rituals of marriage which actually bring a real mathematical effect into how characters are played --
-- then those skills in that category which goblins can't access are things which goblin culture has very little of. Only the most advanced goblins (who had actually achieved a 10 on 2d5 for their Intelligence) would even be capable of conceiving of, or exploiting, the social and ritual practices laid out in higher tiers of the religion skill. Thus goblins do not bury the dead "properly" except in one or two goblin towns which have hit on the practice, and thus zombies plague goblin settlements more often than they do human ones. Thus goblins have not grown to be as large a society as humans.
Likewise, goblin society may have not arrived at magical or scientific processes to reliably cure disease, make stirrups, have a political system more advanced than that of individual clans or chieftains, practice advanced alchemy or undeadcraft, and so on. Whatever stuff is located beyond 60 points in the knowledge trees.
The most elite of goblin intellectuals would be arriving at conclusions which are commonplace in human society, but the bulk of ordinary goblin society -- religion, politics, defense, military tradition, sexuality, etc. -- would be based on a max of 60 points in those subjects for the average goblin.
And yeah -- that does suggest there should be a knowledge skill for the social conception of sexuality. The low ends could be "low tolerance for abnormal or unusual sexualities and preferences", with appropriate mechanical constraints on character behavior. Pass a certain threshold and your character is considered tolerant of said features of other people.
Human characters could start with whatever level you wanted in this skill, whatever is appropriate, maybe based on their Intelligence score or Wisdom or Charisma or whatever you want. Setting a base level of points in this kind of social skill would be an interesting way to replace the background result Alexis (and I) use in our character background generators, in which characters of low to middling Int have a chance to be racially or religiously intolerant for the first few levels of their life.