"However, if the Brothers Grimm could fine-tune the stories to inspire political and social change in their own society...."
We do have to be careful of distinguishing between the 'folktales' that have passed through the hands of collectors and anthologists and those that have come untouched straight from the communities that fostered them - while we have a large collection of the former, our experience over the last thirty years has been with live stortellers from rural area.
Details that appear insignificant have quite often been passed over and even omitted from published collections, while the tellers have often held these details as crucial to the plots - references to the weather or the terrain are an example of this.
I'm pretty certain the in communities that rely on people's abilities to move freely, with a full use of their faculties, disabilities would not just be a plot incidental, but a life-and-death issue to a narrator.
One teller gave us a whole load of tales which began "a man from my own quater (a specific measure of land) and then told us a traditional tale which had become totally localised to his area.
These tales, as fantastical as they are, were direct reflections of the lives of the people who used them.
Jim Carroll