The sad thing is that this is argument is so wrong. She only gained fire powers in Deception (which even then her gameplay certainly didn't revolve around her using fire, it revolves around her flexible, acrobatic moves, she only had a couple of fire moves which were used in a different way from some of the other characters have a fire), she had a purple projectile in MK4. I doubt most of the people who dislike Tanya so strongly only base her on her Deception/Armageddon gameplay, and probably haven't even played as her in MK4.
I've heard people say that she was a Mileena clone, too, which simply couldn't be more wrong. Tanya and Mileena are on the opposite sides of the evil spectrum: Tanya is cunning and intelligent, Mileena is maniacal and savage. The only thing that they even share is that they have Edenian blood flowing through their veins, and their alignment. Saying Tanya is a clone of Mileena is like saying Quan Chi is a clone of Shao Kahn.