Well, TreIII, I guess I look at this way:
Castlevania took what it did, starting in 1987, because of the limitations of what you could do with an immediately understandable action game in two dimensions with the limited and slow hardware of the time. In 2003, you get LoI which takes liberally from DMC, marries it to SotN's Metroidvania styling, and strays away from the N64 games (and I still don't know why since those were arguably better and certainly closer in spirit to the original Castlevania games). Curse of Darkness just followed even closer to the Metroidvania blueprint thanks to the continuing popularity of the GBA and now DS titles. Over a period of 1997 through to today, these releases may have established a clear trend in Castlevania repurposing popular approaches for its own use, ensuring some immediate connection to gamers in the market by its familiarity of play, but they weren't necessary approaches the way being limited to sidescrolling jumping and action was in 1987 on those limited and slow pieces of hardware. The 80s, from which Castlevania was spawned, was still part of the period of primordial ooze where gaming was still evolving into different things, stretching out in different directions, but still quite limited, for action gaming, by the hardware. There's been no such excuse for action titles in the last decade or so, IMO.
The way it's ended up, it's clearly a way to play themselves and the franchise safely, though you can see how that's not gotten them very far on their own when it comes to 3D CVs. At some point, Castlevania made a transition from one form of fairly unique identity to one that sought to more overtly crutch on other games' templates and that was the day SotN was released...for better or worse. I guess that I'm just still so far on the other side of that divide that it's always irksome to see that wonderful style of the original Castlevania treated so poorly as if lacking in any sort of merit today.
