I never freakking understood why they couldn't put more females into the "main character" slots for the shows that they did. Or that the reason they stopped airing the show was because half the viewers were female instead of their freaking target audience.
In the comics their is only 1 female "main" justice league character which is Wonder Woman. Hawkgirl wasn't even an original member but I guess they added her in because of your stated reason. As for the target audience, this has been done many times to cartoons like young justice.