Baffles me why they never chose to follow up SotN with another Metroidvania on the PS1(or even PS2). It was like, "Okay, Castlevania team, you guys did good with SotN! Made the CV series cool again and made the CV series interesting to new fans... so work on handheld games! Yup!". Don't get me wrong, I love the handheld games(some more than others), but I think how much cooler it would've been if IGA wasn't pushed(or pushed himself) to do two mediocre 3D CV game and spent that budget and effort doing some pretty quality 2D CV stuff for the PS2. Is it really because Sony had some beef against non-3D games(strange because of games like Odin Sphere, Guilty Gear and such, which utilize 2D graphics)? If so, I can't help to think anybody that subscribed to that notion hindered the great things that could've been. Hell, I still feel that way now regarding some things with the newere consoles(and how some people think you should ONLY make games for them if "these" qualifications are met). Such mind set is poisonous to all.
My guess is they wanted to bring the SoTN gameplay style to handhelds, and when the first two did well, (one not being an IGA game) Aria happened.
I guess they decided to stick to handhelds to be safe after that, or the games started selling less than SoTN, and by Dawn, just got stuck there because they stopped moving the same numbers, and the 3D experiments kept failing, and they probably figured that a 2D game on the PS2 wouldn't work.
basically, a downward spiral from one harmless idea of going handheld.