You really think Rey's parents plotline wasn't interesting to Johnson? If anything, that issue is given an enormous amount of respect and time in the movie. Just because her parents ended up as nobody doesn't mean he didn't think the plot line was not interesting. The whole movie deals with Rey and her identity and her place in the galaxy, so obviously the issue of her parents and her place in the story was central to the movie.
And as far as JJ's thoughts on the matter, the scene between Maz and Rey further hammers the point home that she came from nothing. I'll also post this interview from 2015:
For me when I heard Obi-Wan say that the Force surrounds us and binds us all together, there was no judgement about who you were. This was something that we could all access. Being strong with the Force didn't mean something scientific, it meant something spiritual. It meant someone who could believe, someone who could reach down to the depths of your feelings and follow this primal energy that was flowing through all of us. I mean, that's what was said in that first film! And there I am sitting in the theater at almost 11 years old and that was a powerful notion. And I think this is what your point was, we would like to believe that when shit gets serious, that you could harness that Force I was told surrounds not just some of us but every living thing. And so, I really feel like the assumption that any character needs to have inherited a certain number of midi-chlorians or needs to be part of a bloodline. It's not that I don't believe that as part of the canon, I'm just saying that at 11 years old, that wasn't where my heart was. And so I respect and adhere to the canon but I also say that the Force has always seemed to me to be more inclusive and stronger than that.
