Not having played it, from what I have seen Overwatch feels very much like a FPS designed to appeal to both sexes. It's loaded with strong female characters that don't feel over sexualized and the game isn't in your typical hyper masculine DOOM/Gears of War setting. I'd wager that if the game proves successful in the long term it may end up showing that it's not FPS in themselves that may be turning off certain female gamer, but other factors related to the story, archetypes and imagery at display.
Agreed though didn't they change a couple characters models because of that? And there is allegedly a ton of Overwatch porn out there.