Maybe yes, its just that when people talk about metroidvania games , they use to say " i prefer iga castlevanias" referring to the concept of metroidvania.
About the woman commenti was referring to an interview i saw on a wikia, where iga says
" think that you become one with the character, and since Castlevania has a lot of male players, it's natural to have male characters. In Rondo of Blood, Maria was a silly, cute aside, but you still had Richter to make it serious. Plus, Mr. Hagihara (the director) had a playful sense of humor. He worked on Symphony as well, and he made the telescope part where, if you pan over to the left you can see a little mouse, and also where Alucard can sit down on the chair and prop his feet up."
"lthough, I purposefully left the Sonia Belmont character (from Castlevania: Legends for GBC) out of the official Castlevania chronology. (laughs) Usually, the vampire storyline motifs, females tend to be sacrificed. It's easier to come up with weak, feminine characters. I'll think about it more in the future, though. It's tough to fit a female hero into the early history of Castlevania, but as you move into the modern day, females can then more easily become a hero."
Well i know on a french forum Iga wasnt liked by everyone, like everywhere there are haters and fans.
Maybe Iga used some ideas from previous castlevanias, but there had never been metroidvanias before, so he most likely brought a lot of concepts all by himself.
The Sorrow episodes are for example extremely addictive because of their soul systems to collect, that bring a kind of gotta catch them all value.
In Sotn, he had that idea of the reversed castle, Alucard has the widest variety of powers of all castlevania games i think(except sorrow games maybe) and a very impressive list of items to find.
The only Metroidvania not made by Iga is Circle of the Moon. It has a nice graphic design, but maybe difficulty wasnt fit for all players. And light problems, i remmber myself trying to play with the sun on my gba to be able to play without hurting my eyes.
I cannot say Circle of the Moon is better than other metroidvanias,its just different. But Iga created the Metroidvania system and made it successful, each episode being awesome, at the exception of Harmony of Dissonance which looked a poor copy paste of Sotn.