I suspect it's part of the pro-monarchy push that started when those folk tales were transformed into literature during the National Romantic period, and later on into other media.
I mean, using royalty as protagonists allows you to use fancier costumes, which would be a non-malicious explanation.
Still, I think that has done some real damage, leading to pervasive #monarchy worship in the modern day, and extremist movements like the #DarkEnlightenment .
I _really_ need to write that German folk tale collection where nobles are clear villains, as an antidote to all that.