I think I'll try my hand at briefly explaining from my perspective why this game doesn't do that much for most people.
Compared to the Ark system games and Ys Seven preceding it, the Action-game gameplay elements are notably weaker. Namely the dungeon design and bosses just don't stand out in the moment and in retrospective as much as most other Ys games. They're just alright. There's usually at least a few bosses fans like to talk about from any game but there's nothing here that I've noticed gets discussed. The final dungeon as well as Lake Tolmes Ruins were the only dungeons that I felt reached the nuance that most dungeons had in Ys Seven for example. A few other ones had an alright atmosphere as well but for the most part there's not much to remember.
Compared to Ys 8 and Ys 9, the party system games that came right after it, the world and lore is pretty uninteresting. There are also far less prettier or memorable locales, ones where the camera angles would slowly unravel and amaze you a ton in Ys 8/9. There's not as much variety in things to do (especially compared to Ys 8 with fishing, raids, more optional areas etc.). Despite Ys 8 and Ys 9 being relatively longer games, I personally felt as if they were paced better than Ys Seven and Celceta (especially in their latter halfs, but particularly because of their unique premises). Ys Seven had a cool main story but it's also 90% full of a ton of McGuffin hunting. Celceta has a more plot driven approach in comparison but it manages to feel even more forgettable than the McGuffin hunting chapters in Ys Seven (those had generally stronger gameplay and music to make up for it).
I don't think I really have anything to say about the specific story and characters, I forget nearly all of it already. The memories of Adol were charming for sure, and I kind of wish more of them had playable segments, while trimming some other fat the game has down. Some of the sidequests also felt more soulful than anything in the main story. I feel it's easy enough to point at the cliche characters and character motivations and the fact that this is a remake of an old game to explain why the story is whatever for most people. Perhaps it's just expected. But nevertheless comparing it to the other party games' stories just proves why it's relatively so unmemorable. Seven's main story (outside of the McGuffin hunting) built a stronger sense of mystique and arguably has the best main antagonist in the series. 8 and 9 had their own interesting story concepts and executed them well enough. Celceta's was just a really typical adventure plot with a really typical antagonist and supporting cast, nothing more or less.
Musically this doesn't stand out much from Falcom's other '00s and '10s OSTs. My two favourite songs happen to be from Kamikura from the jdk band ("The Morning After the Storm" and "Gust of Wind". god damn those guitars). Unisuga, Sonoda and Okajima's contributions otherwise are solid, sometimes great, but they don't stand out too much overall compared to all the other stuff they've done for me and most people.
Other various small things generally felt unremarkable that kind of add up. There's some underwater combat here and it's pretty dull, it's slow and you can only do a basic attack while fishes swerve all around you. Some upgrades such as the Dwarf Bracelet which is really cool at first never get used in interesting ways as some of Ys Seven's powerups did. The Dwarf Bracelet solely exists to let you get through a handful of small spots, it's never used in boss fights (like TLOZ: Minish Cap's often does) or any other interesting ways in dungeons.
There's probably a lot more nitpicks I can make, or more elaboration on major points. Ultimately though this game is just one of those that finds itself in a middle ground lacking the strengths of its predecessors (in this case tight action gameplay) and successors (interesting story, characters and variety).
Compared to the Ark system games and Ys Seven preceding it, the Action-game gameplay elements are notably weaker. Namely the dungeon design and bosses just don't stand out in the moment and in retrospective as much as most other Ys games. They're just alright. There's usually at least a few bosses fans like to talk about from any game but there's nothing here that I've noticed gets discussed. The final dungeon as well as Lake Tolmes Ruins were the only dungeons that I felt reached the nuance that most dungeons had in Ys Seven for example. A few other ones had an alright atmosphere as well but for the most part there's not much to remember.
Compared to Ys 8 and Ys 9, the party system games that came right after it, the world and lore is pretty uninteresting. There are also far less prettier or memorable locales, ones where the camera angles would slowly unravel and amaze you a ton in Ys 8/9. There's not as much variety in things to do (especially compared to Ys 8 with fishing, raids, more optional areas etc.). Despite Ys 8 and Ys 9 being relatively longer games, I personally felt as if they were paced better than Ys Seven and Celceta (especially in their latter halfs, but particularly because of their unique premises). Ys Seven had a cool main story but it's also 90% full of a ton of McGuffin hunting. Celceta has a more plot driven approach in comparison but it manages to feel even more forgettable than the McGuffin hunting chapters in Ys Seven (those had generally stronger gameplay and music to make up for it).
I don't think I really have anything to say about the specific story and characters, I forget nearly all of it already. The memories of Adol were charming for sure, and I kind of wish more of them had playable segments, while trimming some other fat the game has down. Some of the sidequests also felt more soulful than anything in the main story. I feel it's easy enough to point at the cliche characters and character motivations and the fact that this is a remake of an old game to explain why the story is whatever for most people. Perhaps it's just expected. But nevertheless comparing it to the other party games' stories just proves why it's relatively so unmemorable. Seven's main story (outside of the McGuffin hunting) built a stronger sense of mystique and arguably has the best main antagonist in the series. 8 and 9 had their own interesting story concepts and executed them well enough. Celceta's was just a really typical adventure plot with a really typical antagonist and supporting cast, nothing more or less.
Musically this doesn't stand out much from Falcom's other '00s and '10s OSTs. My two favourite songs happen to be from Kamikura from the jdk band ("The Morning After the Storm" and "Gust of Wind". god damn those guitars). Unisuga, Sonoda and Okajima's contributions otherwise are solid, sometimes great, but they don't stand out too much overall compared to all the other stuff they've done for me and most people.
Other various small things generally felt unremarkable that kind of add up. There's some underwater combat here and it's pretty dull, it's slow and you can only do a basic attack while fishes swerve all around you. Some upgrades such as the Dwarf Bracelet which is really cool at first never get used in interesting ways as some of Ys Seven's powerups did. The Dwarf Bracelet solely exists to let you get through a handful of small spots, it's never used in boss fights (like TLOZ: Minish Cap's often does) or any other interesting ways in dungeons.
There's probably a lot more nitpicks I can make, or more elaboration on major points. Ultimately though this game is just one of those that finds itself in a middle ground lacking the strengths of its predecessors (in this case tight action gameplay) and successors (interesting story, characters and variety).