I like this character concept, but that's exactly the problem. There's no instance where Batman can punch this character and the audience loses sympathy for her, or worse, doesn't see Batman as a rich dickhead punching a pseudo-child.
Outside of doing ridiculously evil things that wouldn't make sense (such as Flanderized Joker-esque violence on innocent people) Mary Dahl is entirely sympathetic. Even when she's lighting cartoon dynamite candles in front of her ex co-stars you don't hate her. You don't want to see her nose get bashed in. You just want to see her put down the dynamite and find a better solution. She has a fairly legitimate grievance, having been slighted by fate and big business, and I don't have to tell you most audiences will sympathize with that.
It's the same reason why Mr. Freeze went from a straight villain Batman clocks to this strange anti-hero that DC tries to handle with kid gloves (because, again, if Batman punched a guy trying to resurrect his wife he'd look like the biggest asshole alive.) People sympathize with Freeze the same way they sympathize with Baby Doll.
I see people mention now and then that Mary Dahl was kept out of comics for reasons concerning taste, which I laugh at, since comics are horribly tasteless. But I can see where they're coming from. All it really takes for "that crowd" to form around a character is A) not being ugly and B) giving the audience a reason to care about them. Baby Doll has both of those things, so logically people might read: have
get a little too affectionate toward her. But the biggest reason of all is the simple fact that Batman can't hurt her without it making HIM lose audience sympathy. Even in the 2 episodes she appears in the artists were smart enough to not have him lay a hostile finger on her.
I won't say Baby Doll is a bad character because she isn't conceptually. But she isn't one you can write in a dumb way, which is why she didn't go any farther.