I don't have a lot of personal knowledge of Symphony of the Night (that's the first Castlevania with permanent upgrades that you explore to find, right?). SotN seems like one of those Earthbound sort of games where apparently it is well regarded, but somehow nobody I knew at the time was talking about it at all, so I don't know any of the specifics about what kind of explore-for-upgrades stuff it has. And I haven't played any other recent Castlevania games on the DS or whatever, so my knowledge of the series pretty much ends at Super Castlevania IV.
I ask because of all the recent Metroidvania games I've seen over the past 5-10 years, the exploration/upgrade game design seems to pretty much match what was in Super Metroid. So did Castlevania actually add some new element to that formula, or was SotN pretty much "Super Metroid with a melee character in a castle"? I'd like to know if if the "-vania" part of "Metroidvania" was added just because it was the 2nd series to adopt that style, or because it legitimately added some influential ideas to that style.