I know there's no accounting for consequences and I'm sure there is an explanation, but the fact remains these characters made a sacrifice in MK9 that is now irrelevant. Each resurrected character represents an opportunity to invent a new character or assign a new role to another character.
The ones who died didn't make a sacrifice, they were murdered. Raiden saw their deaths as sacrifices, everyone else (just about) saw their deaths as meaningless. Regardless, sweeping past characters to the side to make way for new characters 'just cause', in some cases, could be acceptable, but on the whole isn't necessary. I'd take true character devolvement over "new" any day.
They obviously haven't. Resurrection is the bane of character development. If they want to ignore or re-write the mk9 church scene (and subsequent dependent scenes) in such a way that these characters don't die, that's one thing but just bringing characters back from the dead is always the worst decision.
What "obviously" makes it seem like they haven't learned their lesson? Here, 2 examples: 1, the right way to bring a character back, and 2, the wrong way.
1. (The Right way) Lao was my favorite character in MK2 and 3 because of his character (he was a stoic pacifist). When he died in 3 he made the ultimate sacrifice (he "death" was for a purpose)...but he came back in MK4/Gold, and he came back for a reason. KL being resurrected in MK4 did hurt his character, or MK as a whole, as he was brought back with dignity and had clear goals. He also, as the story went on in DA and Deception, learned from the past and kept on growing as a character. There were consequences to what happened in the past, and they informed the future.
Now this is getting a bit off topic here, but what hurt KL's character (imo) in the OG timeline was his rewrite in shaolin monks and ultimately mk9. This is what ultimately gets me excited about KL's return in MKX as it creates a potential for him to return to form; the wise, experienced monk who doesn't want to fight, but will. That is what I see with KL's return. And that doesn't take a potential spot away from any one, it creates more opportunity for actual character development.
2. (The Wrong way) Cage's death in MK3, then resurrection in MKT...then his 2nd resurrection in mk4; now that was the absolute wrong way to handle death in MK. You think the characters in mk9 made a sacrifice? Johnny had the most heroic death in all of MK history at the end of MKT...then they fucked it up, big time, by bringing him back. JC became the ultimate joke character in the later games because they didn't know what to do with him...which is why he played such an important role in MKA, and really, why I believe they kept him alive in MK9.
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Over the years NRS has learned a lot about what us fans want to see, and what we expect. I got the sense that NRS understood what we as fans wanted, and what mistakes they themselves made in the past, back in the MKA days, and I'd argue that MK9 proved that they learned those lessons. NRS takes their lore seriously, and I think they are paying more attention than ever before to actual narrative, character development, cohesiveness in story with "no plot holes" (but yeah, nobody is perfect). None of us know how things are going to turn out, but with the comic, and the (I'm sure very expansive) story mode, I think all, or at least most, of our questions/concerns will be addressed.