But what are you basing that off of? Just his past work? That stuff wouldnt be explained? The only thing that I could see that he would do a poor job on was Maz obtaining lukes lightsaber. Just cause of the nature of how he lost it. But Snoke, Reys parentage, I figure he would be able to come up with something interesting. We are talking about Star Wars being backed by Disney! They have all the money in the world to throw at writers and people that can make an amazing movie. Imagine what the Russo Brothers would do if they got to do Ep 8 instead of Ruin. Taking something someone did before (captain america) and making it even more awesome, and cohesive of a story. I think JJ could have done that, I mean, not as good a job as they could have, but at least he respected the fanbase enough with TFA. It still had that same "star wars" feel, of using practical effects, creature design, characters etc
Past work, yes. For example, in Trek '09, there were questions about how we ended up with a rebooted universe and such. That stuff was apparently addressed in a comic book. (It's been a while, so I don't remember the details.) But you also point out another "Wait, WHAT?" moment that just wound up breezed right by.
Also "able to come up with something interesting," isn't (in my opinion) a good way to write. It's better to know where you're headed. You might deviate if, for example, your characters force you to do so or you end up with actors who pass away or who embody something different and inspire you differently, but going in you should know the answers to the questions you're raising instead of "Well, that's the mystery! Ain't it grand?"
The other thing I base it off of -- especially Rey's parents -- is how Rian handled it. While he had free reign, I doubt he acted in complete isolation from the other writers. He and Abrams were apparently interacting while he was writing the screenplay and Abrams was shooting TFA. Basically, I look at what Rian did, and I assume that he didn't go in and simply contradict what Abrams was doing. Abrams might've envisioned the story playing out somewhat differently, but something major like Rey's parents? I don't think Rian would've just said "Nah, that's stupid" and ditched it out of hand. I could be wrong, of course, but that's my guess. I know the films are made where each crew has autonomy to some degree, but there's still supposedly a Story Group, and presumably they are able to say "Yeah, you can't do that because it'll conflict with this other thing."
So, basically, you have four options:
1. Rian knew what JJ was intending, and completely disregarded it and substituted his own thing, thereby throwing the entire arc of the story into chaos...and nobody paid close enough attention or cared enough to do anything. I find this one hard to believe, especially when you look at Rogue One and Solo's production, and how each film had substantial input from the studio saying "No, do it differently."
2. The studio itself is utterly incompetent and has no idea where it's story is going, even in broad strokes, nor what it wants to do, and everything is being done entirely on the fly. Again, I find that hard to believe, albeit somewhat more likely than #1. I think they have a
general idea of where they're headed with the episodes, but not necessarily all the details mapped out. Basically, you can paint with whatever colors you want, but you have to stay within the lines. That's my guess anyway.
3. JJ either didn't know who Rey's parents were and just thought it was neat to raise the question, or JJ had an answer, but it was ultimately unimportant to Rey and her journey. Kind of like how "Where did Snoke come from?" is ultimately unimportant to the events of TFA and TLJ (even if it's important to provide the audience context). So, it'd end up being something relegated to a comic book or whathaveyou. Kinda like "Why is Threepio's arm red?"
orrrrr.....
4. Rian was playing the long game and has been grossly misunderstood by the fan base who expected an answer in Movie 2 because "that's how it works, when the big bad guy tells you the truth about your parents." And in fact, that revelation will come in Movie 3 or later. Remember that TFA doesn't tell you
anything about Rey's parents. It just shows a ship flying away and Rey screaming. We don't even know what
Rey thinks about her parents. We only find that out in TLJ when she meets with Ben. Compare that to ANH, where we had ominous hints about Luke's father from Uncle Owen over dinner, and then Luke telling Obi-Wan that his father was a navigator on a spice freighter, all within the first 30 min or so, after which Obi-Wan tells him "Your dad was a Jedi!" This matters because (1) we know Owen wants to keep him home, and (2) Luke is feeling the pull of adventure, especially after learning that his father was a Jedi. And then in movie 2, we find out, nope,
Vader is his dad! These revelations are as important to Luke as they are to the audience. The best case scenario is that either (a) JJ reveals Rey's true parentage in Ep. IX, and we've now been set up to expect that Rian's version is the truth (when it's really just Rey's own belief), and the reveal is deeply meaningful for Rey, or (b) JJ never touches on the issue and Rian's explanation stands. In either case, what matters is the impact of the information
on Rey, rather than the audience.
My point about JJ's laziness with using the mystery box is that the box is all about audience manipulation, and not about the character. If it matters to the character, I'm fine with a big, shocking reveal. And I mean matters in the sense of "propels them to important action they might not otherwise take." It should be something more than just juicing the audience.