The castle of your dreams.

O One Eru!
Had I been a Christian, I would have become a crusader or an inquisitor to root out heresy.
We don't need any new castles!
A new town will either not fit the general style (like Forge), or it will lack internal consistency (like the aforementioned neutrals' castle).

How is it unclear to you? Maybe you haven't played through the third part enough yet and it seems very diverse to you. But personally, I feel like weeping when choosing a castle before starting the game. My soul demands something new, while my mind suggests that nothing new will come.

We are reasoning hypothetically here, not discussing the implementation of a new castle into the game through collective efforts :D This assumes that the castles would be balanced. As for not fitting into the game—you'd actually have to try hard to achieve that. Forge was far too "alien," and even I, a fan of science fiction, was a bit shocked by such ideas from the developers.