A keen one, yes. But the rules are different if the lord is egotistical with a superiority complex over humans. Such a being would not hide beneath the waves, out of sight; such a being would put his fortress in a place where he can strike fear into those he subjugates, and sit atop the highest tower and look down upon them.
I couldn't have put it better than this. Dracula was a brilliant strategist before, but he let his pride take the best of him. As such, the castle follows suit. It exists purely to instill terror on mankind with its appearance alone.
The castle in itself is a cynical invitation from Dracula - "Are you badass enough to face me, maggot? Then here, this is my castle. Let me see if you have the balls to come here and fight me."
He doesn't want to keep people out of his castle. He wants them to come in and die an humiliating death.
I'm also using this info as an exposition device. Here is a dialogue excerpt:
Alucard:
The Clock Tower is Dracula's final stand against invaders. If the path to the Clock Tower requires any keys, then they may be the only way to reach him. And if the gate is still locked, the keys must be somewhere in this side of the gate.
Julius:
How can you be sure that the key is not on the other side? Wouldn't Dracula have thought of this? Wouldn't the castle want to keep its master safe from all harm? If this is the case, we will have a tough time making it through.
Alucard:
Vampires are naturally sadistic and manipulative creatures. They will find cunning ways to give small hope to their foes, just so they can snatch this hope away from their eyes as they are slaughtered. As a creation from Dracula's will, this castle would not make it impossible for vampire hunters to reach its master, as there would be no enjoyment for him in watching them suffer otherwise. Fortunatelly for us, not even Dracula can fight this basic trait. An inherent flaw in his nature that has allowed us to prevail for centuries.
Why not research a town that actually exists right near one of Vlad III's castles? It would have a more authentic feel in my mind.
This was the first idea. The choosen town was going to be Ocnele Mari - a truly romanian town, where the eclipse reached its peak.
I discarded the idea because Castlevania is not very keen on pointing specific real places. We know it happens in Wallachia, but that is still too general of a place. I can tell you that the story happens on
that small town in the middle of nowhere on Wallachia and it still won't sound strange to you.
Once I start using well-known real locations, dissonance with the real world becomes apparent. An obvious example: do you know about any Romanian town that suferred a strange ocurrence in 1999 that could be explained by the presence of demons attacking it? My research brought nothing that could allow me to squeeze in this story.
While Castlevania refers to real world events while not referring to real world locations, then you can still feel like the story
happened but is kept under wraps - keeping up with the theme of a secret battle of good and evil that permeates the series. Events are much easier to adapt than locations, because locations are things you can physically check anytime. If I tell you that Ocnele Mari was attacked by demons, you could check the town and discover that not only the town is the same as it was in 1999, but no one remembers anything strange happening there. But if I tell you that a town called "Yomi" or "Aljiba" or "Jova" got wiped out, then where will you look? You could say "Ah, but the town never existed! I could check the registers!" but then I'd say "The Church erased all records of it because they must keep Dracula's menace a secret!".
With an invented location, the author is also free to do whatever he pleases with it without risking the reader/player having their suspension of disbelief broken.
This would work if the real location/events taking place in it existed far in the past (and this is why CVIII's "Dracula almost conquered Europe" plot works, as the Church could've had plenty of time to manipulate history to hide this event), but 1999 is too recent, and these real towns still exist.
I might be wrong here, but that's how I perceive it.