Jamie Alexander is no stranger to the action or superhero genre, making her an obvious choice for the role of Wonder Woman. She was in the Arnold Schwarzenegger movie, 'The Last Stand' (one of his later movies, not one of the 80s/90s classics), and 'Kyle XY.' If you're acting alongside Arnold, you probably have a little bit of that bad-ass aura that's necessary to share the screen with him.
She's been in the Thor movies as Sif, a badass fighter from Asgard. That might make a conflict of interests, but it's not as if we haven't seen DC actors become Marvel actors later, like Ryan Reynolds. She's a leading lady as well, starring as the lead in the show 'Blindspot.' Ultimately she didn't quite fit for the role, though she could have easily pulled it off.