Albeit I grew up on Castlevania and few other games, I can agree with what you are saying about how this game was released during the awkward transition from 2D to 3D and how Konami jumped on the bandwagon to an extent. Keep in mind that the Nintendo 64 was very limited in terms of its 2D library out of an entire catalogue of 300+ games and Nintendo wanted to boast that their console could utilize 3D-based polygons. I think the reason that Konami didn't want to develop another 2D Castlevania game on a Nintendo console in my opinion is because they wanted to break away from the traditional 2D style and develop more immersive environments in a 3D environment. Now with that being said, could Konami have waited until Project Dolphin aka the Gamecube to develop a 3D Castlevania when the concept wasn't premature? Most definitely! However, I feel that there would have been some repercussions for Konami if they would have done that. In my personal opinion, Castlevania on the Nintendo 64 was actually somewhat of a decent game from what I remember and it got above-average reviews making it a game that I'd definitely go back and play. I like to think of these games like a social experiment since the concept of 3D gaming was pretty early on and I like to think that Konami took a lot of its inspiration for the game from Super Mario 64 which was highly praised and intuitive for its time. You really aren't missing that much in Dawn of Sorrow depending on how far you've progressed in the story and if you've acquired the correct items for the actual ending. As for Symphony of the Night, I highly recommend finishing the game no matter how hard the game gets. It is definitely worth it in my opinion. Remember though, these games are not meant to be easy haha.
SOTN is one of my favourite games, so after completing the Playstation version I picked up a Saturn copy. Anyone playing it for the first time on the Saturn might not be bothered by this, but in the original Playstation version you can move faster by repeatedly tapping triangle to back-dash in whichever direction you want to go, rather than running. This produces a sort of afterimage effect, which on the Saturn causes slowdown, which is annoying and also makes it take longer, so you can't move as quickly through the castle. Might not bother you if you haven't played the PS version, but just thought I'd mention that as a heads up!
