I'm all for changing a story sometimes, if it works. Maleficent just doesn't do that. I like that she's the "mistress of all evil" for no apparent reason at all. Giving a backstory as to why she's mean ruined it for me (kind of like Ron Howard's How the Grinch Stole Christmas, which gave a backstory on how the Grinch came to hate Christmas, despite the original source material stating no one knew why he hated Christmas). What they did to the Three Good Fairies was wrong. I could go on.
Cinderella wasn't exactly like its animated version, but even if it was, I'd rather watch that over and over again before ever taking time to watch Maleficent again. Beauty and the Beast is great the way it is...why change it? And based on the trailer, I can already tell the live-action version will not be exactly like the animated one.
All of Disney's recent live-action films are cash grabs because they're all animation-to-live-action projects and guaranteed to make money. There's nothing truly original about any of these films, Maleficent included. I can't remember the last time Disney made a truly live-action film that not only received stellar ratings, but also made lots of money.