It was pretty well established that Jor-El was trying to work with the Kryptonian rulers to save Krypton via the codex and they had a back up plan to send Kal away if needed. But if they left without the codex what's the point.
IIRC correctly Jor-El even specifically addresses why he and Lara must stay behind to die on the planet, and its something to the effect that they are part of the doomed structure of Kryptonian civilization (and maybe its genetics). Maybe we can infer from that that if he and Lara were to accompany Kal to his new world, that would in some way compromise whatever genetics plan he has in mind with Kal/the Codex?
But it raises a similar valid 'plothole' question of why Kryptonian civilization inexplicably abandoned its space exploration and colonization program. Why? Why not get off of a dying planet?
I understand the metaphor of the tendency for power to corrupt our souls: i.e., of people with power becoming selfish, controlling, and possessive with it, and deluded by it, blinded and in denial about that very fact, and the self-destructiveness of all that, etc. You could look at the harvesting of the Kryptonian core as similar to the way that we today greedily and mindlessly harvest the earth's natural resources with little regard to the consequences (btw, in the film and especially in its concept art you see the surface of the planet heavily strip mined). But if things get bad enough, that uber-developed Kryptonian survival instinct should have kicked in there to get them off the planet!
It could be that all of the selective genetic engineering that the Kryptonians had been using was actually resulting in an unintended negative consequence of creation of a gene (an unintended mutation) that makes them behave blindly and self-destructively. That would work for me, actually. Jor-El sees it, but its too late to do anything about it as far as the existing Kryptonian civilization is concerned. He knows they are doomed. But he has the plan B with the Codex, Kal, and sending both to earth.
As we know, the Kryptonian civilization is genetically engineered to uphold a caste system. I wonder if the Codex itself will be modified by Kal exercising individual choice. The Codex is now somehow mysteriously bonded into Kal's cell structure. Maybe Jor-El's plan from the getgo is to have the Kryptonian DNA reservoir get modified by Kal's, as he goes through the trial-and-error process of exercising more choice? Just thinking out-loud.
But more concretely, if the Kryptonians showed good sense about finding another world, or if Jor and Lara were to make the journey with Kal, then we really don't have the same myth. Here Snyder was going to make sure that the film stayed true to the source material, i.e., for something so essential.
I think we could probably make a similar criticism for Moses' mother setting her infant son adrift on the Nile. There may have been more sensible choices to be made there 'in real life'. But then we wouldn't have the myth. So I can live with it as a plot device. But I found it intriguing that it is one of the first thoughts that occurred to my wife. As a Superman fan since childhood it's been drilled into my head that that is just how the story goes, lol. Anyhoo, it's a plot device but that's fine.
My gf would rather throw me under a bus than her dogs. In that scene you have to remember Clark is 17, and the last thing he said to Pa Kent was "You're not my father." And Clark tells Lois straight after. "I let my father die because I trusted him." I don't get people not liking this scene it is so emotional. Freaking heartless people around this world.
Actually, for this viewing I noticed that Clark says "Dad, I..." right as Jonathan alerts them to the upcoming storm and they pull over. So just after Clark says "you're not my father" he again calls him dad, which is sweet. And it sounds like he is about to apologize as well.
About Jonathan going back to get the dog... when there is a F4 or 5 tornado approaching literally within yards, my first thought it is perhaps not the best plot device that they could have come up with. (I'm okay with the symbolism of Jonathan dying in the tornado, as I mentioned.)
But in reflecting on it more, this movie is very much about the American cultural ideal/archetype of the power of freedom of individual choice and self-definition. This is a Superman who imo breaks free from the past mold of the character (i.e., a mold that is externally imposed onto the character by American culture circa 1939 - mid 60s) to decide who he is going to be for himself and the world here and now. And Jonathan's death scene actually demonstrates that when we exercise independent judgment we also will sometimes err! Sorry to all devoted pet lovers out there, but Jonathan's life is more important than the dog's. Period. I think it is fair to say that it is without question more important to Martha and Clark. And if one is making the best possible decision, choosing to save his own life over that of the dog is the best one
for his loved ones. But when we exercise the power of choice sometimes we won't always make the best call, and we must live with the consequences. So I think that can be intelligibly read into the scene as part of that final moral/ethical lesson that Jonathan imparts to Clark.
For some reason I think people didn't like the flash backs, but that was so much a better way to enhance the real time scenes and not tell another linear boring origin story.
Yeah, it's not really "pacing" that isn't sitting right with them then, I don't think. The movie proceeds along at a nice even rhythm. Like if it were a beat that steadily drives a song, the use of time isn't all herky-jerky in terms of the changing time signatures, or an unsteady beat, or something. Those viewers are disconcerted by the narrative structure then, and how it shifts between different time periods.
I loved that, myself. I mean, I do respect 'to each their own'--and that some dislike it. But there are enough people that enjoy that kind of narrative structure in this film to assert that it is not poorly executed but simply a matter of taste.