Joss Whedon said this quote

“ Whedon: Studios will tell you: A woman cannot headline an action movie. After The Hunger Games they might stop telling you that a little bit. Whatever you think of the movie, it’s done a great service. And after The Avengers, I think it’s changing.Johansson: A lot of the female superhero movies just suck really badly.Whedon: The suck factor is not small.Johansson: They are really not well made, and already you’re fighting against the tide. There are a couple [female-driven action movies] that have worked-ish, don’t you think?Hemsworth: Angelina Jolie tends to do it pretty well, as the dominant female.Jackson: They got to get The Pro to the screen!Whedon: [Groaning] See, that is the problem. Sam is the problem!Jackson: I love that book!Whedon: [Reluctantly] The Pro is hilarious.Jackson: The Pro’s hilarious. [To the group] You ever see or hear of it?Johansson: No, what’s The Pro?Jackson: It’s [a comic book] about a hooker who gets super powers!Johansson: [Pauses] That is exactly the problem right there.Whedon: That’s why I wasn’t going to bring up The Pro!(From an Entertainment Weekly interview) ”