I agree with Abnormal Freak. Everyone hop on the shit train. I didn't even have cable, so I never saw any of those shows until now.
But yeah, even in the NES Castlevanias, you could see that they were increasingly going toward that darker feel that Super Castlevania IV established. Castlevania II is kinda really really darn obvious about it, but III uses a lot of rich black and shadowing too.
I don't mind the percieved darkness in Super Castlevania IV, it pulls out a strong color palette and even manages to inject some really saturated colors to contrast with everything else. There's a great deal of abstract-ness and patterning in the landscapes too. I loved that Super Castlevania IV retained some of that odd tiling found in the NES titles.

If there's anything I don't entirely love about it, it's the sprites. They're muddy, and lack the technical polish of titles like Rondo's sprites.