It seems that in terms of Gothic literature, Mary Shelley really got the ball rolling with Frankenstein. However, her intent was not to breathe new life into a genre begun earlier with The Castle of Ontranto from 1764. Mary kept the company of her husband Percy as well as Lord Byron, and was in the company of great writers in her home growing up. Byron, Shelley and Keats were Romantic writers of English literature, and greatly influenced by medieval romances. A key element to these earlier forms of literature was magic (or the supernatural).
I think that people are often drawn by what lives outside of the realm of "natural." It cause excitement, provides previously unthought of possibilities, and allows for a place where anything can happen.
If we think back to the stories we "cut our teeth on" when we were children, many of us remember fairytales. And Disney has revived princes, princesses, and wicked witches or wizards, bringing them to the forefront of classic children's stories (and movies) today. Perhaps it brings back to us a time when we were free—even encouraged—to use our imaginations.
The possibilities in these stories are endless: but we are especially captivated by the spells and magic powers of the good and evil, the flying carpets, and the ability to fly. Even the Harry Potter books do this, and though originally intended for an adolescent, have come to appeal just as must to adults.
It's the "stuff that dreams are made of," and I think it appeals because we look outside the normal world to excite our imaginations and feel more alive. However, in these contained environments (books, movies, etc.), we don't need to be afraid, either.