Bingowings said:
From an audience perspective everyone having the potential to wield the Force is more attractive.
These films were designed to appeal to children of all ages so gifting that audience with that potential (albeit fictional) is an aid to making an empathic bond with the protagonist.
We aren't meant to relate to nobility but look up to them. We are meant to relate to boy and girl next door characters.
Having it a skill that only a bloodline of mutants can do is sort of half there because the little kid in the audience may be able to imagine themselves a potential mutant lacking a Jedi Master.
You missed the point...
As I said, the gift should be rare and random. And random implies it can happen to anyone with an equal chance (so yes, farm boys included). The "rare" part makes it unique and appealing, while "random" part makes the possibility that it could happen to you (a casual person).
If something is too accessible, then its loses its appeal. Kids seem to like superhero concept, which is usually the above-mentioned concept: rare and random.