Sadly it seems that Mr. Whedon wants to get a little more, shall we say physical, with the talent if the Rumors out of the Buffy Series are true. This has always been an issue in Hollywood, sometimes they chase the ingenues and sometimes they chase the beefcake.
That aside what Whedon did is loved the material. He loved Captain America, he loved the Avengers and he wouldn’t change the material (more than a smidge or two). This strategy doesn’t always work. Brad Bird Loved/Loves the Barsoom mythos (and clearly knew it well based on how he plotted it). He gave Dejah Thoris more of a part (and far more of a costume) than in the original books, but he didn’t eviscerate/geld John Carter as a hero to do it. Here the issue was the Disney Princess based marketers couldn’t bring themselves to market A Princess of Mars . They couldn’t even bring themselves to call it John Carter of Mars they had no clue how to sell it and so its existence and nature was known only to the more rabid part of the Barsoom fans (e.g. myself). I took my wife and daughters (college/high school age for the girls) and they loved it. They wondered why the heck there was practically no one in the giant IMAX theater on a Saturday PM showing.
Loving the material is a start but is NOT enough. Peter Jackson LOVED Lord of the Rings but was constrained to make 3 movies (albeit nearly 9 hrs in standard form). He loved the Hobbit too but was given FAR to free a rein. In the interests of adding female characters and filling out 3 long films, he padded the heck out of The Hobbit and made a sloppy mess. George Lucas made the original 3 Star Wars films and loved his material and did fairly well until the damnable Ewoks. This is likely because he had his wife (later divorced) riding herd on him as editor. When he made the Prequel Trilogy no one could tell him no and loved himself a little TOO much and he made crap. Many years later Disney said “Hold my beer” and made the sequel trilogy that makes the prequels look like Casablanca or Citizen Kane.
So it looks like the recipe is get a director and/or screen writer that loves the material. Then make sure there is a check to their choices so they don’t go straight up fan boi/fan grrl.
And for heavens sake Disney, please try something NEW. There’s like 20+ marvel movies/tv shows, at least 11 Star wars movies plus hours of TV, Princess movies by the dozens and 4 Toy Stories with a 5th on the way. Try something new and exotic (for you) it can’t hurt more than the last dozen or so flops. And for the love of all that is Holy Send Kathleen Kennedy on an all expense paid 1 year trip to an isolated portion of Borneo with no phone or internet connections. And let Star Wars lie fallow for a couple years that horse (or wookie) is well and truly dead.