I think the reason why you never really see many of the same things explored in later games is because almost all of the earlier Castlevania games were made by different people. Rondo of Blood and Symphony of the Night are the only two I can think of that have the same director (although video game credits in the '80s are sketchy to non-existent), though I think H. Akamatsu directed both Simon's Quest and Dracula's Curse, and possibly even the first game.
And that's one of the biggest things I like about the earlier games: variety. You had different teams making different games all the time. Different designers, programmers, character artists, musicians, etc. Each new game offered something different. Castlevania IV, Rondo, X68000, Bloodlines, and Symphony of the Night are so wildly different in so many ways. It was exciting and fresh. Lately, the games have been stuck being made by the same team (far as I know) with the same producer, character designer, and a lot of the times the same musician. The wonderful variety the Castlevania games always had is now gone, although of course we have Lords of Shadow on the way, but I'm unsure whether to say it's a step in the right direction.
Although apparently Mitsuru Yaida (credited as Yaipon) programmed the multi-directional whip in Castlevania IV, and he's one of the guys who left to form Treasure. Regardless of how involved some of the founding members of Treasure were, however, it's an irrefutable fact that Castlevania IV was made by a studio at Konami and not outsourced. According to the issue of
play that came out around the time of Lament of Innocence, Masahiro Ueno (lead programmer and designer) stated that the game was developed in the Tokyo studio, whereas the original game was developed by the studio in Kobe, which at the time was Konami headquarters.
Super Castlevania IV was not developed in-house by Konami
NO.
Akumajo Dracula Super Famicom 1991.
Treasure Establishment 1992.
The correct answer is here.
The SCV4 programmer "YAIPON" left Konami, and joined Treasure.
The president of Treasure is Masato Maegawa.
programmer of Castlevania Adventure.
And actually, this is probably the most important and informative post in this thread, ha ha.
Sorry if I'm seeming like a dick, by the way. I just don't like the spread of misinformation. It's good this topic was brought up, though.