Clearly, the thing that Supes was searching for on his trek to Krypton (a reconnection to “home,” possible descendants of survivors) was exactly what he found in Jason. In that respect, Jason is the vital resolution element to the alienation theme.
That's very true. But Jason came into play when Superman returned. So taken literally, it doesn't have anything to do with why he left.
When you take him into account upon his return, it does indeed all add up, since Superman felt alienated, and both his departure, and Jason himself, all add up to him wanting to connect to someone.
Btw, at no point in SR is it specified that Supes was tricked into going to Krypton. In any case, it’s not much of a trick. Instead of sending him on a wild, cosmic goose-chase, Lex actually points Supes to the place he wants to go. Odd.
You're right, it wasn't, but that's the problem exactly. Check, if you will, the
Requiem for Krypton making of.
The newspaper intro used there, was actually supposed to be the intro for Superman Returns itself, along with the Return to Krypton scene.
Although no footage exists, Stanford and Luthor's possible scheme detailed tricking Superman away from Earth.
There's also room for subjective interpretation on that part. You could assume Luthor knew it would be laced with Kryptonite, and would literally send Superman to his death.
In the Superman Returns official comic book adaptation (written by Martin Pasko), the scene where Luthor and his gang enter the Fortress of Solitude, actually plays out a little differently.
Bear with me here:
Kitty: Was this his house?
Luthor: You might think that. Most would. But no. He lived among us. This is more of a monument to a long dead and extremely powerful civilization. It's where he learned who he was, and where he came for guidance.
K: What's this, his garage?
L: You're not so far off, Kitty. The leading theory is that he took off in a futile attempt to find his homeworld.
If so, even he would have to rely on a craft of some kind, and I'll bet Gertrude's last dollar that's exactly what used to be parked here.
K: S, did he?... Take off for his homeworld, I mean?
L: Well... we...uhm... gave him a little push.
So far the comic's transcript. But since those scenes don't exist, we'll never know for sure what Singer had planned there.
There you go. You’re taking the movie’s story and plot at face value and then making suggestions for improvements based on the existing structure.
I'm not taking anything at face value. It's just that, Singer (or his team) didn't do a good job at deleting all traces of the footage originally planned. If the newspaper intro was kept, it would have become obvious that Superman announced his departure. That would have also (realistically) explained why the people in the baseball stadium were thrilled to see him.
It's like the others discussed here as well. If he hadn't announced his departure, like the theatrical version suggests, people should have been more hesitant about him returning. They should have been hesitant to a certain point. But they weren't. That's a leftover from that different angle.
Since they probably changed certain aspects of the film during shooting, that also explains why Lois still says Superman left without warning, during their meeting on the rooftop. Because if they had kept the newspaper intro, it would have been clear he actually had, and she would have been less angry with him for it.
It doesn't really matter now, but this is a clear indication that Superman Returns' story could have been so much more.