I don't understand anyone tbh.
Either people want Rosalina to stay in-character as she was in Galaxy as opposed of nowadays , Or they want her to display more of her character in different ways.
Rosalina is a character , a Mario one like any other , It's nothing really special tbh. So , she can jump , run , walk , talk , attack etc. And also it's alright is she is happy , Sad , Angry or dissapointed ; It makes her be a bit more likeable.
Since her former character is pretty pointless at this point , it's alright if Nintendo or any other portray Rosalina in situations in which she is capable of being more ''human'' instead of a robot.
The only thing that's consistent of Rosalina's initial appearence is that , weirdly , she still has that Poker face expression in most of her renders , and even in-game , Which doesn't even match with how she sounds or how she is animated.
With more Spin Off appearences , is only matter of time that Rosalina ends up displaying more human emotions , like she has been doing nowdays ; Imagine if she ever appears in a Mario Strikers game , she would most likeably get upset when she loses or maybe sad , there's a lot they could do.
In the end , at this point it would be kinda hilarious to ask for Rosalina to ''stay in character'' when she is probably the character that has the most inconsistent portrayal overall , Going in Serious in Galaxy , Going Happy In 3D World , Going Annoyingly Happy In Mario Kart 8 , then go back to being Serious in Smash and Mario Golf then go Generic in Mario Party 10.
It's all a back and forth . The only way to truly know Rosalina is playing Mario Galaxy 1 ; If people get to know her for games such as Super Mario 3D World or Mario Kart 8 , they would never imagine she was once a very mature character in her debut.
That's how inconsistent her character has become , and we only know better since we are close to the character , if that wasn't the case then we wouldn't.