I agree with you 1000%. Most people are not judging the game for what it is and in fact are judging it based on what they expected. To add, there are so many contradictory expectations. For example, people hated the Winnie The Pooh worlds in the other KH games...especially because we had to visit them in order to get any extra or secret content. But now, people are mad because Winnie The Pooh now is actually reduced and we don't have to play the whole thing to get secret movies or anything. Another thing...people were literally disappointed we didn't have Coliseums....yet in the past the biggest complaint was that Olympus was lacking as a world because it was made with only Coliseums instead of a real world. The problem with fans of this series is their expectations are not consistent. Its nearly impossible to please every person.
I must also mention that KH2 had the same reaction when it was first released....due to the hype factor and people being let down. Flashforward to today....now KH2 is considered a KH masterpiece. Only time will tell with KH3....
I think you're conflating two different groups of opinions here, like Adrian said above me. But at the same time... a lot of these complaints aren't mutually exclusive. Sure, in KH1 I wish there was more Olympus plot instead of having it be entirely Coliseum based. But... you could still have had more story and areas to explore alongside the tournament. Like what KH2 did, by having a far larger location to explore while still keeping the Coliseum we knew and loved. Why didn't KH3 do that? There was clearly a location for it, a potential story reason, and it's not like they didn't have the ability: The battlegates are essentially just Coliseum fights in other locations, except on their own and without the tournament style fun a restrictions. In previous games, people usually criticized the minigames in Hundred Acre Wood for being poorly designed or too grindy. But they generally like the story beats, and many of the better minigames are still beloved by fans. I hate the bees minigame in RE:COM, but love the hunny slider. In KH3, the world is so pointless. The story is so short and has so little effect as to be practically worthless, it's the same variation of (as far as I can tell) an unfun minigame three times over, and the world is so small compared to every other world in the game. I do agree that while it's nice we don't have to do the minigames to get the Secret Ending... the Lucky Emblems aren't much better. On Beginner, it's almost impossible to find every emblem without either countless hours of searching to find every emblem or looking up a guide. Is it better? Probably, but it still could have been fine tuned a bit.
You're right, it's impossible to please every person. And with a lot of expectations, it's hard to make everyone happy. But KH3 failed in a lot of aspects (and succeeded in many others). It seems like a lot of the crticisms are coming from things that were baseline expected, not over the moon things that should not have been expected.
KH2 definitely didn't have the negative reception this game has had, on the same scale. For sure some people were disappointed, especially with the base game, but I think most fans saw it as an improvement.
And then as a counter To drew0512's point... those aren't mutually exclusive either. KH3 has far more cutscenes than Days, but failed to drum up the same kind of emotional reaction from fans. Personally, I don't think that KH3 has too many cutscenes, I think they're just poorly placed and badly paced. But for people who wanted different interactions, but wanted less cutscenes... it's not too hard to understand what they want. Cut some of the fluff, the unnecessary scenes from certain worlds (AHEM let it go AHEM) and make the pacing better. I mean, look at the Hobbit trilogy versus the LOTR trilogy. Their about the same length, but LOTR makes far better use of it's time. The Hobbit films feel like they drag, so little happens but it takes so long. In LOTR, tons happens, but it feels like a breeze. It's about using the time effectively.