API_KEY_USAGE_PASSED_QUOTA - app passed hourly face operation usage quota
(edit- it's back now. The demo behaves well but it did identify my grandmother as "male".)
Just out of curiosity what are some things you expect people to use the gender selection for? I could imagine a toy app that puts hats on people and, if the gender confidence is high, assigns them a "female" or "male" style hat (and a more unisex style if the confidence is lower).
Why did we added it? Well, "because we could".