I like genre fiction. I don't like the snobbery that can often be aimed against it. Writer and reader know what to expect of each genre. Certain archetypes (character types found to name one example) save a lot of writing and explanation because writer and reader know what to expect. These archetypes can be twisted but there is still the underlying structure which makes the twist work. The twist can't come completely out of the blue. Breaking rules only works when you know what the rules are in the first place.
I have no problems with standard characters like fairy godmothers, witches and so on. What I like to do is make my fairy godmothers and witches unique. I like to put them in situations not found in other fairytales or get them to face dilemmas that when the original fairytales were first written could not have occurred. Fairytales are great vehicles for irony and wit and subtle references to what we know in our "real" world.