I knew exactly what you were referring to. I've enjoyed reading your largely, if not completely, spoiler-free thoughts. I'm a backer that played and contributed a lot of feedback with the demos, but due to various circumstances, it will be a long time before I get to play the final game. From what I've seen/played in the past, I do feel like this is where IGA was taking Castlevania. To be honest, for better or worse, he was gradually turning Castlevania into a new franchise, gameplay and world-wise. So, Bloodstained is sort of fitting. It's just a shame that it came at the consequence of the Castlevania IP being left as a husk for the time being. Because gameplay and IP-wise, I think there are still likely things that "Castlevania" could do that Bloodstained won't. But I could be mistaken.
I think the things a new Castlevania can do that Bloodstained never will are catered to nostalgia (I mean this in a good way) and being fans of Castlevania. For example, bosses in Castlevania tend to be special because many of them are callbacks and frequently recurring enemies. Bosses shared between Curse of the Moon and Ritual of the Night lack the nostalgia pulling power as much as seeing Carmilla as a boss, or Medusa, or wondering how they depict Death. From that perspective, we're more invested in bosses, perhaps uniquely so for such a long running franchise, because there's so many that frequently reappear. In fact, the best bosses in Ritual of the Night are the ones that you could, or even
should, expect from a proper Castlevania game. Then there's the music and the deep, rich history Castlevania has. Everybody expects Vampire Killer, Bloody Tears, or some amazing song to be remixed or even part of an all-new composition, and Bloodstained also lacks the history of game-defining songs, seeing as it's such a new series of games. Finally and important to people like us speaking on a forum devoted to Castlevania, there's the story of the Belmonts and Dracula, and as fans invested in the series, there's a connection between the heroes and the central villain, and knowing there's an arc, an endgame, and a finale to that story that obviously will never be replicated in Bloodstained, as IGA's own personal regrets was sharing a timeline at all, which locked him into the 1999 event with very little windows to expand upon, unless they were all post-Dracula events. If there's one thing he's already not trying to be defined by, it's a set timeline, seeing as he already retconned Curse of the Moon being a prequel to Ritual of the Night, though one of the endings could flow into the game if they chose to create a connection.
Do hope you play it soon, by the way. I really enjoyed it.