Thanks for your super thoughtful reply. I see what you’re saying and it makes sense.
Since I wrote that article I’ve learned a lot more about her backstory which is insanely awful and tragic. Apparently in the comics she’s emotionally and physically tortured by the Joker until she get Stockholm syndrome and (to your point) goes completely insane.
I think the filmmakers weren’t comfortable with pushing her insanity to maybe where it is in the comics. I think because she’s pretty much the protagonist of the story you want to relate to her somehow so they sort of try to make her less crazy?
She might have been more effective as real side character who was just deeply, dangerously psychotic.
But then she wouldn’t be the marketing target that she is now. So I feel like in the interests of selling merchandise to young girls they put her front and center and pulled the punches on her crazy making her this middle ground that doesn’t really work.