2 did flow naturally from 1. I honestly don’t think there’s much in TROS of JJ’s ideas for 2 and 3. I think he got caught up in off-base fan complaints of both TFA and TLJ and he tried to rethink the whole trilogy in one film.
If you read the Artbook for Force Awakens, many ideas from it were used in ROS. For example, Rey sabering an imperial ship, returning to Palpatine’s throne room, the Death Star wreckage underwater, DIO as a variant of BB8’s design, etc.
Samples:
https://i.imgur.com/ioTT9gl.jpg
https://i.imgur.com/0oPFoji.jpg
https://i.imgur.com/D25CcHS.jpg
JJ and his “mystery box” approach worked for getting people interested in the “fresh start” aspect. However, without any actual payoff, TLJ retroactively undoes any intrigue or mysteries of TFA. The surprises of Empire don’t make watching ANH worse in its plot points (for the most part) but TLJ makes all the questions from TFA basically pointless.
They were dumb questions to begin with.
Rey’s parents was kind of interesting but when you don’t answer it and leave us to think about it for a year, then everyone forms clear ideas on who they think they should be
As for everything else, I’d argue it’s less intentional mystery and more Abrams stumbling over his own feet by skipping any kind of backstory. Did you really think Snoke was supposed to be someone we knew? Of course not, because he was just Palpatine 2.0. What Abrams failed to realize was that unlike in ESB, you can’t just introduce the evil ruler of the universe without providing some context. Naturally, people started asking questions about him.
The fact that you even asked the questions at all shows that TFA’s soft reboot worked-AT THE TIME. Lucasfilm should’ve made JJ come up with actual answers to the seeds he planted to get people interested since he is notorious for not even knowing where he’s going. It’s insane how uncoordinated Disney and Lucasfilm were by allowing both JJ and Rian to just do whatever they wanted with the plotline, crossing out each other’s writing like children.
Honestly, I really like how Snoke is set up as the Emperor 2.0 but then Kylo goes “fuck this” and offs him halfway through the trilogy. It’s subversive and it works.
This, however, is one of the few “answers” that Rian came up with that sort of worked.
As for new characters that were introduced in Rise of Skywalker, the two most prominent were both added to the script for the same reason: to shout “No homo”. Zorri doesn’t serve the plot, and is only there to be a romantic interest from Poe’s past. Jannah is meant to be a romantic interest to replace Rey (for the sake of Reylo shippers) and Rose. And there was no way we could allow Poe and Finn to have a romantic connection despite their chemistry, fans, and even actors’ desire… but it’s good to know there’s a line JJ won’t cross for fan service.
That’s what I mean about last minute character additions. They felt like they should’ve been introduced in 2 rather than the finale. As it turns out, none of the characters introduced in 2 or 3 were as interesting as of TFA’s mystery box characters. At the time, Rey, Finn, Kylo were interesting because we didn’t know their histories in the SW universe. They were new concepts that grew out of the old real life lore–a black, rebellious stormtrooper? A new mystery female Jedi? A psychotic “What Anakin was supposed to act like” emotional Sith? These were new, different takes on what people were used to. JJ is a terrible writer but he comes up with good concepts, and people cared about these new 3 leads.
Then we have the new characters introduced in 2 and 3. Did most audiences really care about Holdo, Rose, the literally unnamed DJ, Jannah, or Zorri? Snoke had potential but that was cut off before anything could grow.
This is why I say there may be a way to edit down the extra characters and side plots to focus on what the sequel trilogy’s main focus came down to be: one or two people’s relationship deciding the fate of the galaxy. It’s a bit of a rehash of the OT, and the PT for that matter…but maybe that’s what the sequels should be, to some degree?