A lot of the history or the Mirror Universe has been fleshed out in those episodes. And really it’s a pirate universe, that gets boring fast, hard to find room for external plots when it’s important to have your main cast trying to kill each other every movie.
Reboots are about having it both ways, that is why you do them. Keep the concept ditch the canon. New stories within the broader universe still have to drag around the canon, if you do a Gorns vs Tholians movie somebody points out how the two could never have met due to some single sentence somewhere. That’s the canon problem, it chokes stories to death.
The writers took the smart route the “no we aren’t watching 28 years of TV and 10 movies most of which actually suck just to write one damn movie” route. Reboots happen all the time, every 3rd freaking James Bond movie is a reboot, Trek fans just need to suck it up. Because really, their whining about the sanctity of a canon that never really even existed is WHY a reboot HAD to be done and should have been done 2 or 3 times by now.
You win, it is the most brilliant concept since Ishtar. At least this will not have two Darrins in it.
It's kind of like saying to a patriot we're changing the American flag to a hammer and sickle. Suck it up.
This remake doesn't even make sense. Even if the time line has been changed, when Kirk's father dies, the previous point of time did not. Before the Romulans had come through the Black Hole, the time line had not changed and there would be no reason why Khan would be any different than what the original series had made him to be.
If JJ had any brains, he would have picked up one of the other episodes and made a film instead of taking an already highly successful movie and re-making it.