I also do not think warframe has a "lack of exposition" issue, it has a "the pacing is extremely bad because all the quests are trying to cram multiple hours worth of concepts and story into usually around 40 mins where it cannot fit these bigger concepts into that time frame and thus the exposition gets sidelined to random collectibles" issue. It's not the lack of exposition, with the exemption of constellations (which as much as I love it, has many issues), it's the exposition is usually hidden where you cannot expect the average player to go and they are never told about in game.
This is the case for the original Jade Shadows, if the entirety of Jade's Promise was in the quest, it would've held a lot more emotional weight. This is also the case for things like Duviri, Angels of the Zeriman, arguably Whispers in the walls, New War, arguably 1999 given it's hidden ending, etc. etc. DE hates giving explanations withing the quest itself, for what I can only imagine is dev time and wanting to keep their schedule on top of running a con that only gets bigger every year. You cannot keep relying on Kim to give your story the bone it needs.
To me, what makes Constellations especially egregious is that it fails on both these fronts:
1. It's pacing is abysmal. It is so bad I don't get how it got past a writers desk with how quickly it moves for something that needed way more time to breathe. Even without gameplay, just on paper the story is moving way too fast. The emotional scenes lack any weight, because they do not have any weight.
You are never told that Hunhow was even dealing with the man in the wall in the background, you are never told about the deal itself except when it's already made, the "void stone" feels like a mcguffin that can just do whatever you want it to and only exists just for this one scene. You could've replaced it with a toaster and it would've meant the exact same thing.
Stalker is just told his son is back from a doomed future and there's two of them before he is forced to fight them. They do not speak. Sirius and Orion despite supposedly coming back for him do not even acknowledge his existence. You could've replaced Stalker with any other character in his own story for that scene and that's bad. Despite the story being about reuniting a family, all of them have very little interaction in their actual story. Sirius and Orion don't even have a voice.
You could literally replace the protoframes with two kavats and nothing would change. Genuinely. I do not care about their lines for when they're skins and on crew, they have actually no personality in the quest and on the railjack missions themselves. The quest didn't need them at all. This would've been a lot better if it was just Sirius and Orion as bosses instead, then they could've had lines and personality and it would make a lot more sense when Stalker shows up to ask them what they've learned in normal missions. There is actually no reason other than money for protos to be shoe-horned in here and it makes me genuinely worried for Tau that we're going to have 1 more shoe-horned in where all they do is subtract from the story.
2. There is no exposition outside of the quest content. You do not learn about the doomed futures, the protos still have basically no personality, you never find out if these protos are made by Entrati or where they even come from, there's a random mention of Neci on the posters and that's about it. Hunhow has some interesting lines with his space dementia, but... nothing else. Nothing more than voice lines and some hidden signas that also do not expand on the story in any way.
There's not even any new codex entries or syndicate to rank up to find out something more. There is absolutely nothing. Why is there nothing? I can only imagine it was tennocon crunch, but that also brings up the question as to why hype up this update so much to begin with? Yes I understand it was supposed to bring a close to Stalker's story, but it really doesn't do more than that despite setting up bigger concepts. I hope we see those bigger concepts actually realized in Tau, but I would be lying if I said I didn't think it was extremely cheap to leave a bunch of loose threads just to be like "Yeah! Wait for the end of year update in December!" if they ever get revisited at all.
Over all I liked constellations, but my god does it have issues writing wise. I hope those don't bleed into Tau. Old Peace had some of those pacing issues, but not nearly as egregious as this. DE please just slow down and let quests be multiple hours, I promise no ones going to complain as long as they get a good story out of it.