The problem is that this is an MCU movie. This is a setting where Bruce Banner- I mean, Bruce Banner, the poster child for the insecure introvert- is a wisecracking comedian. This has been the formula since it worked the first time with RDJ. Thor is a wisecracking comedian. So is Ant-Man. Captain America escaped that somewhat somehow. But it's what the character is written to be. Right in the script, other characters say she jokes too much. No matter who was cast, she would be saying those lines and having to play it essentially as she did.
Now it may have been the directing, telling her to play it like that. But the point is that it's an MCU movie no matter what and that's the formula so it seems strange that she gets the flack for something that is almost every main character and sometimes to far more of an extreme than in this movie (Thor 3 comes to mind).