SOC is definitely a bit focused on the specific elements of the Imperium (or similar) setting, true. Of course that isn't a BAD baseline, as
@pemerton has noted. It casts the game into a sort of "Age of Sail" kind of mold where travel and communications are slow, and sometimes unreliable, but there is still a widespread society. The only problems I see with Traveler is it kind of (even the setting specific materials) never REALLY delved into the legal, cultural, and social structure of the Imperium. What sort of rights, powers, social conventions, wealth, etc. adhere to the various social levels within the Imperium? We really do not know. Even Spinward Marches doesn't really make that clear. It also seems as though there is an 'Imperial Culture' and then 'Local Culture' (as well as Law, Govt., Economy, etc.). How things are factored is really never explained, at all. We can draw some very tentative general conclusions from the rules, but in a lot of ways the setting is close to non-existent.
So the 'SOC' ability score is very hard to interpret in Traveler. What does a 15 represent? Does that make your PC a very high ranking Imperial noble? What does that mean? How does that relate to your status in the local culture? Aside from a few tables modifiers what exactly does this very high status do for you? Nothing at all is ever stated about this. I mean, if this was a Medieval European society of, say, the 11th Century, then being high ranking nobility is a huge big deal. You can practically exercise life and death over almost anyone you meet who is a commoner. Certainly over anyone who is your subject, and EVERYONE is a subject of some nobles, unless maybe they are citizens of a free city or something. Is the Imperium similar, or does 'nobility' mean something else? It is REALLY not clear, so SOC can't do a whole lot...
Of course the GM can deal with these types of questions. However its tricky since you would assume every PC would have deep knowledge of these questions, so you will have to create answers with a good bit of detail when it comes up, or again devalue SOC and things based on it by making them "whatever is convenient right now."