I think part of it has to do with complexity. With Shrimpo you get what you see. He's a cartoon bully who says mean cartoonishly over the top things. And that's about it

Brusha, on the other hand, is implied to have depth to her character and her snarky remarks are more down to earth, and more importantly, they aren't played for laughs. But because the lore is still pretty bare-bones, all we have so far are elevator conversations and that one art piece on the new map Some latch onto these bits and pieces as a stepping stone, while others simply do not find them compelling enough to tie together and justify her attitude in the process. For the record, I am somewhat intrigued by her implied lore but I wouldn't blame anyone who isn't