I think they use the Disney stuff because they can. They were given free reign of the Disney vault, tons of free material, no copyright infringement. And the most familiar material to I’m going to hazard, the majority of their audience. Tons of people honestly haven’t ever read the fairy tales anymore. A lot of people don’t know what really happened to the little mermaid.
It was sort of a given once you found out a) Snow White was awakened by a kiss b) the dwarfs had their Disney names and c) Jiminy Cricket vs. nameless cricket that you were going to see Disney characters.
If there is a Disney version of the story, I believe we will always see nods to it. If there’s no Disney version of it, then you have a much better chance of it focusing more on how it was originally.
At the same time, there just doesn’t seem to be a chance of us really getting the gruesomeness some original fairy tales had. The chopping off of body parts and I’m pretty sure cannibalism (all those roasted human hearts and livers people wanted to eat) isn’t going to pass an 8pm network tv standard. Admittedly, I’m not all that broken up about that particular aspect.