Well, we really don't know that, actually. The fact is, ANY IP that Kojima does is going to sell millions, regardless of what it is. So I don't think they really gain much by rebranding something else as Castlevania. I suspect that this was meant to be, from the ground up, a Castlevania game, but they decided to stray considerably from the norm, because the series needed a reboot. And we really don't know much about it yet. The truth could be that when we actually stick this game in, it may be immediately apparent that it is indeed a Castlevania game.
All I'm saying is, let's wait until more info becomes available before we start condemning aspects of the game that we really don't know about.