Checkpoints in story quests
I’ve wanted this very same thing. The game crashes for me an obscene number of times (today more than ever) especially in personal story missions. Forging the Pact was a particularly annoying one for me because the game would normally crash -after- I defeated the boss, but before I spoke to the npc. Awful!
A checkpoint is a great idea, or even keeping the instance “on hold” for 5 minutes or so, just to give those who d/c or crash and chance to get back in there and finish up the stories. It would relieve a whole lot of stress, for sure.