It’s not that she’s not a nuanced character. It’s that those are the first things that people learn about her, and in a 2 hour movie when you’re the fifth lead there is no time to dig past that to the nuance, particularly without the voice over tactics they can use in comics. How much nuance did say c3po get in the original Star Wars? Or Cyborg in Justice League? As a minor character in an action movie you get maybe three traits to work with. And in Cass the would be 1. Ninja 2. Heart of gold 3. Not a talker which is every Asian sidekick since Bruce Lee put on his chauffer’s cap.