I'm not sure I agree with this. One of the main protagonists of The First Law is a very privileged noble. Prince of Thorns and Prince of Nothing are about, well, princes. And Lord of the Rings' main true hero is the most humble of them class wise. Looking at some other trad fantasy... the main characters of The Wheel of Time are common rural folk. The Belgariad is about a farm boy who's bullied onto a throne. Claiming the throne is a secondary plot in The Riftwar Cycle with much of it focused on keep orphans, ******* blacksmiths, and common tribesmen doing remarkable things. The Fionavar Tapestry is about five ordinary real world teenagers. And so on. A more cynical look at class? Maybe. But a different focus on the class of characters? I don't think I see that.
And I really don't think after two and a bit books of selfless and wise service, we're meant to root for Aragorn being king because of his bloodline and not because of his personal qualities. Yes, Tolkien attaches a lot of importance to bloodline and the divine right of kings, but he really goes out of his way to show that Aragorn has the personal qualities - and personal qualities attached to having lived a humble life.
@The Big Peat - that's a great reply, and when I first read it I thought you'd clearly demolished my argument. However:
The ethos of the nobility is that they are superior to the rest of humanity because of their bloodlines, and therefore must lead by example in this.
The Lord of the Rings underlines this philosophy at every opportunity. Aragorn is not a noble because he is a great person - he is a great person
because he is noble. I'm not so familiar with LOTR than many others here, but I would be surprised if any kings were ordinarily shown in a bad light - where they are it is shown to be due to magic and other evil influences (Theoden). While lesser men may be capable of acts of nobility (Farmir), their impure blood makes them incapable of being truly noble, which is why the Lords of Gondor may never be kings, only stewards, with Denethor and Boromir demonstrating the weakness of lesser men.
Bilbo and Frodo extend this as expressions of country gentry. They have no job or employment commitments, merely a comfortable financial position that allows them time for idle leisure and travel if and when it suits them. They are therefore absolutely neither common nor working class. Samwise, however, is, and therefore must respect Frodo as his master, a point repeatedly made. Despite any allusion to friendship, Samwise will never be Frodo's equal.
As for Abercrombie, he subverts these class values in his First Law trilogy: Jezal is nobility who is selfishly interested only in protecting his own social position, and ultimately incapable of putting compassion for others first; Glotka, on the other hand, has been expunged by the nobility into a low class position, and despite the horror of his employment, proves to be the only character capable of caring for others. Logen is just a commoner whose story in the
First Law trilogy ends with him in exactly the same position as he started.
Back to nobility - Feist and Jordan both write about farm boys with hidden heritage/destiny: Rand and Pug are both demi-gods in the making, so their low-class origins become meaningless. Am not familiar with the
Belgariad, but I will be surprised if it's about commoners winning out against the nobility.
Prince of Thorns read to me as a YA book, and I'm not sure it's particularly grimdark - that reputation seems built entirely on Jorg claiming that he is a rapist at the start of the book, but the content is otherwise relatively docile.
Lord of the Rings has ... grimdark tropes
If we define "grimdark" by content then LOTR is a very grimdark and depressing book. After all, everyone fails, and most of the characters "die" at the end! But we've seen multiple arguments about defining what "grimdark" is on these forums over the years. I suspect that trying to define it by content is a distraction: simply put, I would suggest that grimdark in the fantasy genre is nothing more than a reaction to the simplistic morality of classic fantasy where nobility is good by default. Thus by rejecting class as a fundamental designation of what is good and evil, "grimdark" becomes dependent on relative morality, resulting in "grey" characters and "grey" plot developments.
Or, perhaps grimdark is nothing more than a secular rejection of traditional religious morality, of which the divine right of kings (and the extended nobility) is simply one facet?
Anyway, just thinking aloud.