The Little Mermaid is not a folktale. It was created by Hans Christian Andersen, mostly out of whole cloth. And the "strong and moral message" is, to me, an example of a kind of morality that I very much hope is dead (very much about scaring children, for instance).
Really, I can't see what is so incredibly good about the original fairy tales, from some sort of artistic or Bob forbid moral perspective. That includes original creators like Andersen as well as people who worked with existing fairy tales like Perrault and the brothers Grimm (and usually reworked in in the process - something which has been done with stories from the dawn of time).