Dan Jurgens isn't the best writer in the world. He's good at gimmicks that sell comics...in fact, all he really did was turn the old imaginary stories into "real" stories- the death and wedding. And Zero Hour was just plain awful...it was like "Look at me! I can do Crisis on Infinite Earths too! I'm cleaning house!"
Actaully the wedding was a 'real' story before Jurgens did it. See the online comic "Superman Takes a Wife." (Action #484) writen by Cary Bates which has the 'original' Superman (Earth-2) finally marrying Superman.
During the Silver and more so in the Bronze age Superman's powerlevel had gone up and up and away. We even had a joke about how powerful
Superman was during this period:
Superman saves a forgotten civilization in the Andromida galaxy, then moves a planet out of the way of a comet in Quazar 26 100 million light years from Earth, and finally saves Lois Lane from Lex Luthor all in 2.2 seconds. "Slow Day" thinks Superman.
Superman was so powerful that magic and even Krytonite were appearing with annoying regularity. Byrne's reboot brought some badly needed fresh air to Superman. But things started to go haywire when it became clear that the Legion books were not going to reboot their history despite the fact LSH v3 #18 had left them a perfect out to get rid of Superboy and the whole 9 yards.
Then DC had it Legends crossover which shoved the LSH continuty problems in everybody's face. Then they had the LSH try and find out what was going on and so the Pocket Universe was created though Byrne had it an alternate reality while the Legion writers in typical blundering fasion had is a Pre-Crisis world the Trapper somehow saved (if history was rewritten their wouldn't be anything for the Trapper so save. He exists at the
end of time not the beginning). Then the grim and gritty hits both books and aside for the few bright spots (like the early part of the Dominus saga) things basicly go south.