While I agree with the sentiment that characters from MK 4 shouldn't just be passed over, you need context too of where they would fit in the story. Tanya's story was that after Edenia was freed, she betrayed her people in order to keep herself alive and to potentially gain more power. In this timeline Sindel is given Shang Tsungs power, leading to her being too overpowered for the Earthrealm forces to stop and, in theory, help restore her memories and free Edenia. No freed Edenia means it's not something Shinnok was targeting, thus leading to there being no reason to really align themselves with Tanya due to there being no real plus side to the Neatherealm forces. Her entire story arc from MK4 is kinda irrelevant due to the chances.
Fujin is making appearences, which is good, because he has reason to. Of course, as long as he's still alive, Fujin should really be involved with everything ever beside Raiden. Quan Chi and Shinnok are there, Reiko is all over the comics, even Jarek made a cameo. The only character that hasn't made an appearence from MK4 that I can't come up with an easy in story explanation story for is Kai. But that could just be "Oh, he died during the battle" or whatever. Heck, you could say his death could have been during Mortal Kombat 9's Shaolin raid by the Tarkatans, as being the first "relevant" time line split if you really wanted to.