If the spoilers for this movie are true, why should I trust they'll do anything good with her in future? At least in the comics, "Avengers Disassembled" and "House of M" were outliers and "Children's Crusade" was just bringing her back to the hero she usually was.
It's true the MCU has treated her all right up until now, but if they do this story, they're telling the world that she can't be trusted to do good and that the people who hated her in "WandaVision" were right. And if they'd make such a horrible choice, I'd rather they kill her off than see what else they have planned, because their idea of a good Wanda story has been corrupted.
It's just unfair that other characters get to be heroes and all Wanda gets is a stupid line pointing out that she's the only character who gets treated this way. If their idea of a good story is for her just to get worse and worse, they shouldn't be using her.