Just to be clear, when I say classicvanias (and I believe I mentioned something like this before in the thread) I'm not including VK and CV2. I obviously acknowledge those as being radical departures from CV1's genre, to the point where people occasionally point to them for precursors to SotN's style rather than lumping them in with CV1 and its formula.
But I'm not really clear on the motivation for the list of what was different in CV3, HC, 4, Rondo, CVA2 and Bloodlines, since it actually sorta seems like you're acknowledging they've got little in the way of major changes to the CV1 formula. You also neglected to mention CVA1, CVChronicles, Legends, Dracula X, and Adventure Rebirth for some reason; I guess because they didn't have notable differences worth mentioning from what came before.
Also, for Bloodlines, I'm not really sure different locales rather than just castles are notable for it alone--CV3, 4, Dracula X, and Rondo all have outdoor areas or areas leading up to the castle which aren't castle interior, like caves, forests and other varied environments. I wouldn't say that's an innovation belonging to Bloodlines. More to CV2 and then most of the classics ran with it partially until you get to the castle. Bloodlines does take place all throughout Europe rather than in one location in Europe, but a forest in Greece and a forest in Wallachia doesn't really make much difference to the player. There are some iconic landmarks used as locations though, but I'm not really sure that's significant enough that I'd say it's an innovation.
Also, the 8 directional whipping innovation seems to be mostly a hitbox variation issue, of which most castleroids have in spades. Each new entry has a decent number of new weapon hitboxes (compared to SotN), especially in something like OoE with spells as regular weapons.
On the castleroid descriptions, it seems like your basic definition of their formula and justification for why they end up the same is that they're all "going around the map, acquiring new abilities to progress further." Let me try to critique this a bit. The problem is, with that type of loose description and justification, you do indeed end up acknowledging a great deal of video games as clones of each other and make it difficult for much innovation beyond major genre or structural changes to be satisfactory. Most Zeldas turn into "Find dungeon, solve puzzles, collect special items, use those items to progress and beat the dungeon boss, repeat." 2D Mario turns into "run through the stages platforming, stomp on enemies and defeat the boss at the end of the level." There simply aren't enough genres out there to allow us to complain about a series sticking with one, only adding a major change every once and awhile, and changing minor bits and pieces the rest of the time (like the RPG system changes which you don't acknowledge as mattering much).
Finally, things like the HoD spell book system or the OoE glyph system I agree are mostly only minor changes in ways of doing things the games to some extent did before, but I wouldn't exactly lump the partner system in PoR in with that. That's a more significant change to the way the player handles the gameplay, commanding the partner to use specials effectively and it also adds extra physical puzzle elements occasionally for how to interact with the partner to progress. For example, swapping to one to push a statue that'd be out of reach for the other so the other can jump up, commanding the other to stand in a particular location to use his/her shoulders as an extra platform, pushing on a train concurrently with both to slow it down enough or the go-kart segment where you swap between them concurrently to avoid obstacles to get them both to the other side. While I didn't really like the addition of the physical puzzle elements much, they were still there.