It's significantly more complex than Java due to the borrow checker and lifetimes in generics.

I don't think Rust is all that complex. On the other hand Java has many obscure features like serialVersionUID. For that matter, even fucking JavaScript is more complex than Rust with its var vs let, == vs ===, how, e.g., an empty array is false, parsing Date, how to make a "deep copy," etc, and TypeScript's type system can run Doom.