You are right, and you forgot how overly sentimental it is to appeal to feelings rather than logic.
Also, how does time travel work? Sometimes you have different time lines (G'raha from ShB) sometimes you don't, like in EW. They tell you you can't change anything and all of a sudden you might as well be the cause of the Final Days. If we hadn't been there, would it all had been the same? Elpis just took place so we met the final boss and it didn't feel as it had appeared out of the blue and to go full fanservice. And what with the meteor showers? Why did they happen?
All in all, I enjoyed the story, but I was expecting a lot more and I hate time travels precisely because these kinds of things happens.