Sorry this is not exact: The common Idea of a fairy tale was definitlly not "a conventional misconception based on sanitized versions of the stories published for commercial exploitation in the late 19th and early 20th centuries. "
The Idea to collect them was an original romantic Idea of the Brothers Grimm, directly inspired aswell from Clemens Brentanos Collection "Des Knaben Wunderhorn" as by Herder's Theory of sentimental education by those deep rooted stories which hitherto survived for long time only in aural tradition not at least characterized by the stories the old womans (grand mother) of the traditional family told when they took care for the children while the Parent worked.
The Grimm Brothers expressivly intended this collection to be for Children and called them from the beginning "Kinder und Hausmärchen". Yes there are some passages of atrocity in some tales but the overall character is dominated even in those tales by the always very conciliatory end of each tale. It might even be that some tales have been mitigated by the Grimm Brothers. But of course not "in the late 19th and early 20th century". This is simply not true. It was Grimms Collection that shaped the common Idea of a fairy tale and it was from the beginning in Grimms very romantic understandng of the fairy tales inteded to do so exactly in the way it does.
Sorry for bothering you with german literary studies but since the Grimm- Brothers startet their work nearly 200 Years ago exactly in the town where I write in this moment this posting, this might clear some misconception about the Idea of the Fairy Tale and who have had which conception of it. So believe me it is no misconception to make a significant difference between atrocity stories and the fairy tales in Grimms Collection.
To get an impression of the musical understanding of "Märchen" in the early and middle 19th century just listen to Schumanns Märchenbilder, for Viola and Piano which is very warm music full of very romantic emotions. I do not think this might be in any way a "a conventional misconception based on sanitized versions of the stories published for commercial exploitation in the late 19th and early 20th centuries. "