[SoundingShores]

I think Beren and Luthien can be seen, to some extent, as "forerunners" to the Hobbits. They certainly have that First Age glory about them, but compared to the other, great forces participating in the conflicts of their time, they were still "little people." They even infiltrated an enemy stronghold like Frodo and Sam.

An important difference is that the anti-Sauron cause was supposed to be more or less purely righteous, and this goes also for the people of higher social status who fought the war, not just the Hobbits. Sure, some had less elevated motives than others, but they weren't fighting Sauron for downright "sinful" reasons (except maybe Saruman). By contrast, the oath of Feanor was supposed to be blasphemous against the Valar, so their entire reason for fighting was basically bad from the start. And then there was the Kinslaying. Because of this, they were morally compromised and couldn't be allowed to get what they wanted. In fact, their adherence to their oath had to be ruinous, in order to portray rebelliousness against the Valar as misguided.

Beren and Luthien, by contrast, didn't have this possessiveness about the Silmaril or antagonism towards the Valar, so they could be allowed to have some degree of success. And as with the Hobbits, allowing smaller players to fulfill unexpectedly large roles helps create a sense that everything is part of some grand inscrutable design (which is clearly what Tolkien wanted to suggest).