If that's the case, it's not if she "fits" that's the problem, but rather the superflouosness of her character, as there's already others fulfilling that role.
I can get behind that, however, MKX was about the next generation of those roles. Like, the former military characters, shaolin monks and ninjas passing the mantle to a new generation.
It would basically mean that in MK11, if NRS goes through with it, we wouldn't have Sonya, Jax, Johnny, Scorpion, Kung Lao and Liu Kang, because now Cassie, Jacqui, Kung Jin and Takeda have taken over their roles.
... but knowing NRS, I suspect they won't go through with that.