The appeal of Grimm stories for Disney lies in their potential for creating visually stunning and emotionally resonant movies. The characters and conflicts in these stories can be developed and expanded upon to create memorable cinematic experiences. Plus, they have a cultural significance that adds depth and heritage to Disney's filmography.
One reason could be that Grimm stories have classic and enduring elements that appeal to a wide audience. They often have moral lessons and engaging plots that translate well to the big screen.