This was probably answered, but...
-Why are Kitana and Liu Kang playable if they remained revenants and turned actually into rulers of the Netherrealm, ie potential boss material? Please don't tell me it's just for the sake of sales and pleasing old fans. That would be pathetic.
That's the only thing I really disliked. Yes, just for sales. But why not keep both as revenants instead of presenting us a scam false old Liu Kang?
-What's up with Sareena? She just appears out of nowhere. Half of the people have no clue who she is and all they come up with is one sentence to explain her origin. Then she disappears again god knows where.
She was an informer. They treated her as they already know her for some time. Makes no difference, we all know who she is.
-What's up with Fujin. Similar case. He just shows up at the beginning, cool, and then bam... gone. Sure, he's more known, but where does he go? And why? Just doesn't make any sense. Even less sense after learning he was supposed to be in more scenes, but they cut him back. Then why put him in in the first place if all he is going to do, being quite important, is have a few lines? Why even bother making a new costume for literally just 5% of the story?
I agree, Fujin should have been at the least with Raiden. Of course he was doing something else.
-Why no background on Ferra/Torr? Are they supposed to look mysterious? Dumb? Or both?
Check their ending.
-Why show a Fatality code input for killing Baraka, but no input for Mileena? Same character. Again a small wtf for me.
Probably because they did want something different from her standard fatalities.
-Bi-Han mentioned by Sareena, yet no explanation?
Probably mention to MKM:SZ.
-Sub-Zero killed Sektor. M'kay. Why not show it? Or even better why not include it and let us fight Sektor? All they show is remaining circuits. An iconic character is ridden of, yet all they do is this. Kind of insulting. Easy way out.
-What happened to Cyrax? Sub-Zero killed him too? Cyrax is even less important so they not bother to mention him at all?
-With these two dead, are there any cyborgs left? MK without cyborgs not MK. Maybe Smoke in MK11?
Sub-Zero's chapter was used as mentor, not to tell Lin Kuei's story. He only said that so he could help Hanzo. With that formation, unfortunately, we could never see him defeat Sektor.
-Did they kill them off on purpose just to leave more space for Predator? If yes, they must've decided on DLC a long time ago.
I don't think we have enough evidence.
-What's up with Kano? Never got back to him. So he's alive in prison? Or did Sonya in the end anyway decided to kill him?
IMO it was obvious Sonya arrested him.
-Is Quan-Chi dead for good or not?
As it seems, yes. Of course not forever.
-What was the spell he was casting? Did he want to trap himself inside the amulet? Or was that a spell to release Shinnok?
No, that spell was the spell to release Shinnok. There was no reason for him to be trapped there...not even escaping Hanzo. He was Shinnok's only hope. When he saw he would die anyway, he at the least completed his job.
-Shinnok is sorta dead. What will happen to him now? Kitana and Liu will play ball with him?
Nor dead or alive. After his best role since forever, maybe he will be a trophy. Anyway, that was a warning.
-Raiden turned Dark. OK. So he's the big bad of MK11 then? Cause when Boon said "surprise returning character" we all expected someone else than Shinnok. No surprises it seems.
We have no evidence to say it.
-What happened with Frost? Did Sub-Zero kill her? Bury her? Teach her?
We don't know. But knowing Sub-Zero, he didn't kill her.
-What happened to Bo Rai Cho? Same as Fujin... 5% and disappears.
Good question.
Because Kotal.
- What happened to Rain and Tanya?
Lost the rebellion. They were a coup inside the rebellion, there was no space for their schemes.
-Is Shang Tsung somewhere? If not, why do some of the character intros mention him? What happened to him anyway?
Many endings point not only to his resurrection, but give him new ambient for a return.