I've played a fuckton of MMO's and none have done the story much better. The only exception is maybe The Secret World. Most MMO's have pacing issues out the ass when if comes to story. I've played 40 hours of FF14:ARR and I don't know at all where the story is going. Same for Guild Wars 2, Vindictus, and plenty of other MMO's. On top of that, Kingdom Hearts is terrible at storytelling. In every game but KH1 and BBS, you are visiting worlds for the sake of filler, mainly because they seem too damned scared to deviate far from the Disney originals to create an actual connected narrative. KH2 is one of the worst offenders: visit once for nostalgia, twice for plot. Lots of fluff and filler and eventually a story. Is it okay? Fuck no. But I'm not going to lie to myself and expect an immediately awesome story from a KH game. I'm not giving them a pass, I'm asking why in thee fuck were you expecting better. Look at their track record and keep your expectations in check. I ain't justifying a damn thing.
Again, there is a big fucking difference between the way Chi handles its story vs. how higher quality MMOs do things, even if they do them in a very MMO-y stretched out way. FFXIV ARR's storytelling is hardly perfect, but even with all its flaws & pacing-issues, there is SOME kind of story to everything. With the main story, there is proper build-up where you spend a fairly long time getting to know A LOT of different people & become a part of the group trying to fight against the powers that they are up against. And when the story DOES take steps forward, those are some pretty lengthy steps instead of the 3-year drip-feed that is KH Chi, in which - even after 3 years - the story is still extremely vague with details, bigger context, character motivations & such. The game has been hitting us in the head with the same vague storybeats for a long time without giving us all that much additional, meaningful new info.
Even the most mundane quest in something like FFXIV usually serves some purpose for someone in the world & has a little bit of backstory, build-up & pay-off to it (except maybe some tutorial-like missions & monster hunts), even if it's not super exciting or relevant to the main story. In Chi, you go to Agrabah and try to find that "special Heartless" that took the monkey with him, except about 5 gazillion Agrabah missions in, we've pretty much forgotten the damn monkey and accomplished NOTHING except run back & forth in the fucking desert.
Chi's form of storytelling goes like this: "hey, maybe this completely irrelevant character X is over here? No, then maybe he's over here? No, not there either, let's go to this place instead? Nope, not here, maybe we should go back to the place we started at!" for 40 missions in a single location, then you don't even find said character X because who knows why. Then the cat bitch comes along and says "hey, how about we go to a new world for no reason!" and then you do the same thing all over again without NOTHING advancing in any kind of meaningful way. Then, about 500000 missions in, you get the first proper story cutscene that lasts all of 1,5 minutes (if even that) and even that story scene really doesn't push the story forward more than a few nanometers.
Even non-mandatory side quests in FFXIV have an actual structure. You maybe get the back story (maybe a merchant who deals weapons who sent an apprentice to go get some stuff from the next town that is the main producer of said stuff), then you have to backtrack the apprentice's steps and find out he has strayed off the main road for some reason. Then you find him being harassed by some thugs, who turn out to be hired goons of some competitor of the merchant, this leads you to an additional 2-3 mission questline where you try to serve some justice to this scum competitor who tried to harm the merchant's apprentice. As a surprise twist it turns out the merchant you had originally helped had done shit to the competitor first and the competitor was just trying to get back at the the merchant. Yes, something like that is not the most original or exciting thing to experience, but at least it gives you some context & purpose while also doing some subtle world-building.
An MMO like FFXIV might not be some kind of masterclass example of storytelling & pacing, but it's about a million light years beyond the likes of Chi. Same goes for other KH games. Even if games like KHII & DDD have Disney stories that don't have all that much to do with the main storyline, the Disney world mini story arcs advance at a pretty brisk pace, often do have at least some short story-relevant cutscenes. And you aren't trapped in Agrabah for 70 hours chasing shadows before you get to the next world, only to return to Agrabah for 90 hours later on, STILL just to chase those same shadows (and still not getting anything done). So even if their relevance to the bigger whole can be brought under question, there at least IS some story with a beginning and (a temporary) end during your first 2-3+ hour visit to the Mulan world in KHII.
Days might be a bit boring with how much sea-salt ice cream you have to watch Roxas & Co eat, but there IS some kind of story arc there where it starts with an emotionless Roxas just existing with no purpose or meaning to his life, who then starts to develop a personality little by little and ends with him having bonded with two other people so strongly that he's willing to fight for them. The dialogue might suck. The pacing might be off. But at least the friendship forming between Roxas, Axel & Xion feels somewhat believable and the drama that starts to surround Xion as Org XIII advances with their plans creates some intrigue and emotional investment to the situation in comparison to Chi where you meet some dude for 2-3 times and then suddenly they are the bestest of friends who'd fight until death to save each other. Or something. It doesn't feel earned because even WHEN you see these characters together, the interactions feel shallow & too short to make their bonding feel earned.