Eh, I am not surprised. A game released for the PS3, 360 and PC is easy to port from one console to another. Different controllers, better graphics, that's seemingly easy. But to adapt one of those games so that it works with the gimmicky tablet controller from the WiiU sounds like a hassle. They would probably have to redo the whole game from scratch to maybe fit the items menu in there or add some touch screen controllers...
Now, if they were to made a Castlevania game specifically for the WiiU, it would be a completely different story.