1. No One Sees Action Movies Starring Women
...unless it's Tomb Raider or any of the Resident Evil movies or Kill Bill or Charlie's Angels or OH SHIT The Hunger Games, that one made an assload of money. Other than those movies (oh also the Alien franchise), no one sees action movies starring women. Making good movies isn't the key here, it's all about the gender of the lead.
(oh right and Salt, too)
2. No Respected Writer/Director Wants Anywhere Near The Project
...let alone one with any geek credibility and/or familiarity with projects focusing on superpowered women. Well, except when Joss Whedon was trying to get one made. Ya know, before he did The Avengers. Which made like $1.5 billion. Other than him, no one - that's why they had no choice but to say "Yes" to a television pilot from David E. Kelley, the creator of Ally McBeal and other legal dramas starring quirky professionals and not ever superheroes. A television pilot that ended up like a terrible version of a David E. Kelley show that didn't understand how to utilize a superhero lead, which no one could have seen coming.
3. Wonder Woman's Powers Are Stupid
They would look ridiculous on-screen. I mean, c'mon, previous iterations of her powers would look downright silly. An invisible jet? Sure, they could drop that (as modern comics mostly have), but that would be pretty unprecedented to change anything from a comic's history (except for Spider-Man's organic web-shooters, Jean Grey's origins, and every superhero movie ever). DC needs to stick to only making movies about heroes whose abilities have never looked dumb (haha, by the way, remember when Green Lantern's weakness was "the color yellow", like the entire COLOR, like a banana could hurt him? Weird!)
4. There's No Actress Who Could Play Wonder Woman
Who would possibly play the title character? There's no one who could be this iconic superhero but also bring the star power necessary to guarantee a successful box office. No one at all. No onegelinajolie oops haha typo, I meant Angelina-Jolie-and-OMG-Brad-Pitt-Could-Be-Steven-Trevor-Holy-Shit-Do-That-And-You-Will-Make-So-Much-Goddamn-Money.
5. Uh, No, Because Angelina Jolie's Way Too Old
Actually wait - that wouldn't work! Because Angelina Jolie's way too old! I mean, she's 38 years old. That's so old! Remember when Robert Downey Jr. started as Iron Man when he was 43? And audiences everywhere rejected him immediately and the box office of Iron Man and the Iron Man-centric Avengers film reflect how terrible of a decision it was to hire him.
6. Wonder Woman Is NOT Batman
DC has figured out that the only way to guarantee huge success from their superhero movies is to include Batman. Last we checked, Wonder Woman is NOT Batman.
7. Hollywood Already Tried Some Female-Centric Comic Book Movies and They Did Bad So That's That
Remember how bad Catwoman did? Female-centric comic book movies can just never work. It had nothing to do with the movie being an ungodly trainwreck on every possible level of production and everything with having someone with two X chromosomes in the lead. That's in no way a sexist attitude - remember when Jonah Hex bombed and Hollywood stopped making male-centric comic book movies? I mean, they did right?