My big theory on this is Shane's letter that he wrote after V3. Shane spends an entire page whining about how a fight between Raven and JNPR was cut when it would have likely been a mess, alongside mentioning that Adam was meant to have a full fight with Yang. But Shane never mentions anything about Adam as a character, and given how the letter goes into a lot of detail on M&K 'ruining Monty's vision' or somesuch, I feel like Miles or Kerry entirely throwing Adam's character out to make him an abusive hate-sink would have been something Shane got livid about.
I think this is the problem with people that defend "Monty's vision". The man was an amazing animator, and he loved his anime, and he did fantastic work doing all the groundwork, but he was also a terrible writer. But I don't hold this against him because he knew his limits.
For starters this:
"Geography determines your culture and culture determines your people-Monty Oum""
That quote alone explains why RWBY had a bad start (story-wise) where the heroes didn't even know the villains existed after 4 seasons.
That might, and I say that with a huge grain of salt because I don't agree with Tabula rasa, be true in real life, but for writing that is wrong on so many levels. It's actually backward. I have some writer friends that love creating worlds, civilizations, and even entire universes, but they lose sight of what matters the most in a story: The characters.
In a story, the characters define both the culture and geography your story needs.
Tolkien might be an exception because his stories were just an excuse for his languages and world-building, but I would also argue that save for his die-hard fans, the stories that really resonated with the general public are character-based (The Hobbit and LOTR). Gandalf is part of Pop Culture; "Numenor" is not.
I sincerely doubt Monty's vision was anything more complex than "cute anime girls kick a lot of ass". I think in the long run Monty would've been happy with keeping animating an amazing choreography, but his vision still needed a competent writing team to take it beyond mere eye candy.
I'm aware Monty did have some ideas like why Ozpin didn't have a name based on color, but what actually needed work was the plot and how his characters would grow and develop as people.