After Soma Cruz thing I wouldn't call Belmont=Dracula thing - sensationalism.
If magical schoolboy being Dracula and Japanese priests sealing castle in solar eclipse are not sloppy storytelling, I don't know what it is...
I don't think that as a bare concept is inately bad. I mean, Dracula could be reborn as ANYBODY, and when he was, he would be "christened" into modern society/pop culture. He'd grow up and attend school as a "schoolboy". That's logical. The Japanese thing, just another nod at the multi-cultural aspects of the Castlevania series. Dracula's rule was dominant over the dark entities of ALL different cultures and mythology, so it's only natural that other cultures(outside of Europe) could feel threatened by Dracula's power, especially during the Demon Castle War. And of course, the Japanese have their own rich mysticism. Now I don't think Hakuba(Mina's father) did it alone(it was likely a combined effort of whomever was there, to weaken the Castle/Dracula to the point that it could be sealed away), but I never wrote off the whole mutli-cultural mysticism thing. I think it's actually more interesting than keeping things STRICTLY European.
I find that funny, in a way. The Japanese, for being really culturally proud of their history, when they make stories(anime, games, manga), they have no hesitation in pulling from many different cultural mythologies. The result is the creation of worlds that are almost a sort of ethnic/cultural melange, a mixture of both East and West as one. You rarely see that with Western stories or games. It DOES happen every now and then. Star Wars is pretty much a mixture of multi-cultural ideas. But in general, the stark contrast between an European-type setting and "non-European" is pretty big. Maybe it has a lot to do with Western "logic". You don't see too much highly flamboyant or imaginative fantasy from the West because more "grounded" and realistic fantasy(I always laugh at those two words being used side-by-side" are the more acceptable forms of the genre. The West, the motto seems to be, "That which is feasible is correct!", while Japan's motto seems to be, "Anything imaginable can exist as you say it to be!".