In fact, what I've advocated in the past is flipping a coin at script stage to determine the gender of any character with a speaking part whose gender isn't determined by something plot specific (such as a heterosexual character's love interest). If 70 supporting characters in the cast from Trek 09, it would take maybe 10 minutes tops. Seems simple enough.
And if they flip the coin and it comes out with 55 men and 15 women you'll be crying foul as well.
When your spending $200 million of your own money to finance a film or are hired to direct one, then those decisions will be yours to make. Until then, your only requirement is to decide whether or not you will financially support the product.