South Park: The Stick of Truth was very specific in how it handled the player character, you were forced to be a male and the story reflected that through dialogue. This is something that which we were fine with, but wished that the option to be a girl was there, and as it turns out this feature will included in The Fractured But Whole, as revealed by Matt Stone and Trey Parker in an interview with Entertainment Weekly.
They shared a recount of the experience with Stick of Truth and how this affected the decision to include a female playable character for the sequel, they stated:
"In Stick of Truth we got halfway through the game, and we had narratively come up with the big Girls' Quest halfway through it. [The Girls] were a faction in the fantasy world. And then someone's like, 'What if you want to be a girl?'"
"Narratively, it didn't work. We'd have to sh- can the whole game. So we just left it the way it was. This time, we obviously wanted to add that."
To make things cooler, much like how certain people (more often the girls) would react to your boy in Stick of Truth, the same affect will happen if you play as a girl in the new game, essentially making this truly feel like South Park. Matt and Trey continued on:
"The boys are little boys, because it's really a story about little boys running around. So they don't care about [your character being a girl]? That seems weird," Stone added. "They always seemed to care about it in the show. Are they dumb about it, and they don't know? So you're in hiding? Or do they totally care about that, and totally treat you differently? So we ended up doing those things differently for different characters."
"It's been a funny journey to go through, introducing something that we thought would just be a cool feature. You're a girl! But now they're going to treat you different."
Matt Stone shared a bit about his personal preference when it comes to games, and told the interviewer that he prefers to play as a female character when given the option. They even figured that "We figured everyone's gonna pick it."
I can't say that everyone is going to want to play as a girl, but the option is appreciated and could add a lot to the game. I expect that the dialogue could be exceptionally hilarious.