Sean Gates, writer of the independent film L. Frank Baum's The Wonderful Wizard of Oz wrote a Facebook note about feminism in Baum's works, especially The Wonderful Wizard of Oz. I'd recommend going over and reading that now, because it brings up some points I'd like to discuss below.
Baum's mother-in-law was women's rights activist Matilda Gage. While he had some hesitation about her (after all, his marrying Maud ended Matilda's dreams of a self-reliant daughter), once they accepted each other, Baum really respected her views, and as Michael Patrick Hearn points out in his Annotated Wizard of Oz, they found their way into the Oz books. As Sean points out, both Glinda and Dorothy defy the stereotypes they would fit in normal fairy tales.
The strong feminine characters are part of what makes Oz unique. Usually, the male characters are strong, but in Wonderful Wizard, Dorothy's friends feel inadequate and the Wizard, despite his noble intentions, has no actual magic power.
Now, unfortunately, mainstream movies don't seem to be able to capture the same unique sense of feminism. I would not attribute this to the writers, directors, and actresses of being unable to capture this. Rather, it's too different from what mainstream movies do. Because what they do is a business. They don't make movies with "let's make a game-changing movie that will set new standards in the film industry" in mind first, it's "let's make something that will sell." (On a business level, I understand this. As an artist, I find it disgusting.)
And unfortunately, rather than improve on the characterizations, they'd rather sell you over the top action and gore, CGI special effects and 3D.
The feminism of Baum has never been successfully captured on film by a mainstream producer, except in Disney's Return to Oz, where while Dorothy is scared, she is quite capable of finding solutions to her predicaments.
Sean mentioned the flaws of the MGM characterization of Dorothy, which has influenced many depictions since. One notable exception has been the film version of The Wiz, but the making Dorothy an insecure adult was problematic and does not reflect Baum's feminist themes.
Some of the more substantial depictions have been from foreign producers, one of the better versions being the anime series in the late 1980s. Dorothy is yet the leading force in the story, despite its alteration.
Frankly, I'm looking forward to Sean and Clayton's movie. By being independent, they don't have to worry about paying back investors and a studio getting in the way of what they want to do (although I'm sure they wouldn't mind if some studio threw some money their way). And, I sincerely hope, we'll finally see an onscreen version of Oz that was everything Baum intended it to be.