Fire attacks are her main suit. She is also a sorceress in black magic, hence why she can also shoot purple projectiles, can levitate at times, etc. Even though she has usually used fire and small amounts of black magic, that doesn't mean they cant differentiate the types she uses. Not only that, with that logic you're basically saying that Liu Kang isn't needed because Kung Lao has shaolin styles and Scorpion has fire balls so Kang is pretty much not needed special moves wise.
I'm not saying that at all, because movesets aren't that important to me! You brought them up. I simply disagreed that Tanya's is at all interesting.
Please elaborate a bit more.
I did with my next point in that post! But to elaborate in depth: in very well written stories, characters' actions are always consistent with who those characters are, and help us to understand them and find depth in the story. In Mortal Kombat... the actions are quite divorced from the characters.
"Liu Kang beat Shao Kahn three times." Well, what can I take away from that about Liu Kang's character? Is he that determined? Is he that courageous? Is he that stubborn? Is he that altruistic? None of these? All of these? Who knows? He's just "the main guy" and he beat Shao Kahn because he was supposed to beat Shao Kahn. He's not really a character.
So when you say that "Tanya was instrumental to helping put Shinnok in power," I don't know what to do with that information, and because MKX is in a new timeline where events aren't meant to repeat themselves, I don't know how NRS could use that to make her interesting again.
She's an edenian ambassador. She's treacherous to survive, not to acquire power (besides MKA ending). Quan chi can do much more than her but that doesn't dismiss it. They both have completely different styles of Sorcery. Quan chi relies on portals, skulls, and possession techniques while Tanya mostly only experiments in 2-3 forms of black magic.
I don't really care about sorcery, I want to know how her motivations and goals would be different from other characters. Take the situation with Kitana and Jade in MK9, Jade was horribly written because she was just a Kitana clone. She had literally the same arc (Shao Kahn's henchwoman realizes she has been deceived, runs off to join Raiden), and the same motivation (stopping Shao Kahn) as Kitana. I don't want to ever see anything like that again in an MK game.
So for example, Reptile joins Kotal Kahn because Kotal will restore his people, D'Vorah joins him because she loves him, Erron Black joins him because he's promised money, Ermac joins him because Ermac is programmed to help Outworld's Emperor, and Ferra/Torr join him because they like to beat people up. Great, each character has a different motivation and different goals, so then depending on what happens in the story, they can become more interesting. (Kotal Kahn fails and has no money to pay Erron Black, does Erron Black betray Kotal Kahn, or is Erron secretly a good guy and he'll help Kotal anyway?)
Scorpion is different from Shinnok's other lackeys because he's out for revenge. Quan Chi and Noob Saibot are both power-hungry (a terrible motivation, but whatever). And Tanya would be with Shinnok because... she wants...?