There was already a nerd-rage inducing part to that film so having a woman as the true villain would have gotten a double whammy of whinging dickheads.
Honestly though given Tony Stark's status as the world's most epic poon-hound he'd be very vulnerable to a femme fatale type character.
Honestly though given Tony Stark's status as the world's most epic poon-hound he'd be very vulnerable to a femme fatale type character.