I don't think it's fair to say that the series is going downhill, or that it is losing its idendity game after game, as if every game that comes is somewhat worse than the previous entries. At worst, I can see the series being inconsistent except in the music and graphic deparment, each game presenting a series of higher highs and lower lows than the previous entries. For example, the use of FF characters went downhill after KH2, but DDD went and incorporated TWEWY characters in more a meaningful way, to then drop all type of direct crossover until ReMind (and only for fan-service). The lowest point in the series regarding exploration and world design was KH2, specially vanilla KH2 where it was practically non-existent, and bbs, DDD and KH3 at least tried to expand on the idea of exploration, one with better results than the others.
Regarding the storyline, is it a mess? Yeah, but it has been a mess since KH turned from a stand-alone game to a game series. In the first two entries after KH1 the storyline already played the concepts of doppelganger, "the other me", time travel (briefly), resurrection, idendity theft, deconstruction of binarism... Every game afterwards have mostly played again with those concepts or expand the importance of those. Is it Nomura fault? Mostly. He relies to much on complex tropes to generate a false sense of deep meaning to his storylines, explains the bare minimum for the player to barely understand the game's storyline through big exposition moments and then relies on deus ex machina to solve most of the conflicts because the ideas behind the conflicts requires an incredibly high level of world building that do not fit into a 20-30h main campaign game that needs to be kid-young friendly. The complexity of the concepts he uses also cuts short a lot of possibilities for character development, as the time required to move the main plot forward when the game can actually talk about its own thing is so much that character to character interactions and character insights are relegated to secondary importance.
On defense of Nomura though, I do think he has really cool ideas on paper for the concepts of the games and the characters he creates. I do like the idea behind the BbS trio conflict of trust, and the sea salt trio of mortality salience and self-awareness that their time together is limited. It is the way those plays out that feels messy most of the time. Also, even if the road from point A to point B both regarding characters and plot points leaves a lot to be desired, Nomura makes it in a way that almost everything, someday, will make sense, and he will present it in a way that will generate excitement or fells in most players. Taking Riku's return at the end of KH2 and Aqua's return in KH3 as examples, even if in the first case Riku was mostly non existent through the game and a big part of his character development happened off screen and the second one comes after the decision of turn Aqua "bad" because... she was keyblade-less threw into a pool of darkness, most players still cares about those moments and were moved by them. And we know they actually know how to showcase more sides of the characters and their interactions, taking RAX and SDG as an example of a believable friendship.
Regarding Disney, I just don't understand the big problem being discussed now. Amazing Disney incorporation into the main plot and the bigger picture only happened in KH1. Every game after that game was a step down. However, I do feel like some games have at least tried to implement Disney concepts in a better way than their precesors, specially KH3. Yes, Arandelle is horrible in those regards, there is almost 0 interaction even with Sora and Disney put a lot of restrictions... but all the other worlds mostly go from fine to really great? I mean judging by post-KH1 standards. Setting aside personal preferences about the games or the Disney movies, I cannot understand those who claim "objectively" that Disney is worse in each entry, as if BbS and KH3 worlds were less meaningful than those in KH2 to the overal experience. I actually believe the contrary? I have expent a lot of time during the quarentine diving again into KH lore and KH world building, and it actually reinforced that notion. And for those missing Disney boss figths, while some of them could have been amazing (Randall, he actually have a power), there is no one to blame but the entertainement industry that is changing, and villains such as Hans and Mother Gothel are no more powerfull wizards with dark magic, but humans with more realistic approach of their motivations and ways of obtaining them. And I actually don't think that's a bad thing.
As final note, I do think KH1 is overall the most cohesive experience. Is a simplier story, where original concepts mixed with Disney and FF blend perfectly in almost every aspect of the game (story, gameplay, exploration, minigames...), and something like that haven't been present since the original KH. However, I do understand that to go back to that model Nomura would have to complete reboot the series, go for a more stand-alone-ish approach, and put himself a lot of restriction in his creation of new characters and storylines to make them blend as well as they did in KH1. And while I don't think any game post-KH1 have achieved such a level of cohesion, I do think every game in the series has done something great or even better thats their precesors. Combat in KH2 appeals much more to the players than that of KH1 for a reason, and recently KH3 combat is for many better than that of KH2 or almost as good. Exploration and world design have been improved a lot, in how bigger, different from each other they have become, and how some of them feel more alive than ever. And while I love KH1 for what it is and it's still my favorite KH as a whole, I find some storyline concepts that came in later games fascinating. It misses most of the time in the development to feel like an amazing piece of fantasy storytelling, but the ideas are there and I still belive it captures most of the essence of what KH means.
Regarding the storyline, is it a mess? Yeah, but it has been a mess since KH turned from a stand-alone game to a game series. In the first two entries after KH1 the storyline already played the concepts of doppelganger, "the other me", time travel (briefly), resurrection, idendity theft, deconstruction of binarism... Every game afterwards have mostly played again with those concepts or expand the importance of those. Is it Nomura fault? Mostly. He relies to much on complex tropes to generate a false sense of deep meaning to his storylines, explains the bare minimum for the player to barely understand the game's storyline through big exposition moments and then relies on deus ex machina to solve most of the conflicts because the ideas behind the conflicts requires an incredibly high level of world building that do not fit into a 20-30h main campaign game that needs to be kid-young friendly. The complexity of the concepts he uses also cuts short a lot of possibilities for character development, as the time required to move the main plot forward when the game can actually talk about its own thing is so much that character to character interactions and character insights are relegated to secondary importance.
On defense of Nomura though, I do think he has really cool ideas on paper for the concepts of the games and the characters he creates. I do like the idea behind the BbS trio conflict of trust, and the sea salt trio of mortality salience and self-awareness that their time together is limited. It is the way those plays out that feels messy most of the time. Also, even if the road from point A to point B both regarding characters and plot points leaves a lot to be desired, Nomura makes it in a way that almost everything, someday, will make sense, and he will present it in a way that will generate excitement or fells in most players. Taking Riku's return at the end of KH2 and Aqua's return in KH3 as examples, even if in the first case Riku was mostly non existent through the game and a big part of his character development happened off screen and the second one comes after the decision of turn Aqua "bad" because... she was keyblade-less threw into a pool of darkness, most players still cares about those moments and were moved by them. And we know they actually know how to showcase more sides of the characters and their interactions, taking RAX and SDG as an example of a believable friendship.
Regarding Disney, I just don't understand the big problem being discussed now. Amazing Disney incorporation into the main plot and the bigger picture only happened in KH1. Every game after that game was a step down. However, I do feel like some games have at least tried to implement Disney concepts in a better way than their precesors, specially KH3. Yes, Arandelle is horrible in those regards, there is almost 0 interaction even with Sora and Disney put a lot of restrictions... but all the other worlds mostly go from fine to really great? I mean judging by post-KH1 standards. Setting aside personal preferences about the games or the Disney movies, I cannot understand those who claim "objectively" that Disney is worse in each entry, as if BbS and KH3 worlds were less meaningful than those in KH2 to the overal experience. I actually believe the contrary? I have expent a lot of time during the quarentine diving again into KH lore and KH world building, and it actually reinforced that notion. And for those missing Disney boss figths, while some of them could have been amazing (Randall, he actually have a power), there is no one to blame but the entertainement industry that is changing, and villains such as Hans and Mother Gothel are no more powerfull wizards with dark magic, but humans with more realistic approach of their motivations and ways of obtaining them. And I actually don't think that's a bad thing.
As final note, I do think KH1 is overall the most cohesive experience. Is a simplier story, where original concepts mixed with Disney and FF blend perfectly in almost every aspect of the game (story, gameplay, exploration, minigames...), and something like that haven't been present since the original KH. However, I do understand that to go back to that model Nomura would have to complete reboot the series, go for a more stand-alone-ish approach, and put himself a lot of restriction in his creation of new characters and storylines to make them blend as well as they did in KH1. And while I don't think any game post-KH1 have achieved such a level of cohesion, I do think every game in the series has done something great or even better thats their precesors. Combat in KH2 appeals much more to the players than that of KH1 for a reason, and recently KH3 combat is for many better than that of KH2 or almost as good. Exploration and world design have been improved a lot, in how bigger, different from each other they have become, and how some of them feel more alive than ever. And while I love KH1 for what it is and it's still my favorite KH as a whole, I find some storyline concepts that came in later games fascinating. It misses most of the time in the development to feel like an amazing piece of fantasy storytelling, but the ideas are there and I still belive it captures most of the essence of what KH means.
