Not to be sentimental, but I really hold respect for Yamazaki as a writer for committing to what the story/characters need instead of what the audience wants.
I really cannot fathom how Chise and Elias living in isolation would have been a "better option" or "better writing" for the characters, considering that both were deprived of all kind of experiences and connections.
Now, Chise is just a few steps away from adulthood. The conception of the story is her life in this beautiful world that welcomes her after meeting Elias. But the gear that moves the story has always been their growth. Without it, none of the events would have their own purpose, just as any story without sense of development would be meaningless.
And while I'm not particulary super invested in the Beast arc -at least for now-, I do appreciate that it's still loyal to its roots about the growth of one's self in the face of adversity, and the bonds that are formed between humans and non-humans (plus all the historical context and how it's linked to myths. That's super interesting).
Source: INTERVIEW: The Ancient Magus’ Bride’s Creator and Editor Dive Into Its Mythological Aspects and Success. Anime Trending. 2024