I can't speak for everyone, and I'm just stepping into this conversation, but.....
The things you mention are mostly outside factors. Other than a few notable exceptions (like Jon setting the cat on fire) most of the stuff that happened to the Kents happened because of forces beyond their household. There was, for all intent and purpose, very little internal struggle within the family.
Now, Clark and Lois are exceptional people; they're smart, clever, confident in themselves and each other, and accustomed to the weirdest things imaginable being thrown at them. They're not going to have stupid, mundane struggles where they suspect each other of cheating or something (and the stories where they do have such foolish problems are among my most hated Super-tales). But they're still going to have problems. And we didn't see a ton of that. Most of what we saw were aliens screwing up family night. Even many of the problems we saw within the family felt like they were just there to show how amazing the family is. Jon lit the cat on fire? Well, he feels appropriately bad about it and when he finally works up the courage to admit what he did his parents are understanding and cool, and already knew anyway. They were just waiting for Jon to be ready. How utterly perfect a parental response is that? I have probably never had such a perfect handle on parenting in my ten years as a father.
The (internal) issues we saw within the Kent house often felt like they were just there so the family would have some (relatively) minor obstacle of overcome together, thus proving their perfection as a unit.
I think that a big part of the disconnect here (for me anyway) is that we didn't get to see Clark and Lois grow into these new roles, and we didn't get to see Jon be raised. By the time we're introduced to the concept, Jon is well on his way to growing up and his parents have had a decade's worth of practice to figure things out. I never saw either of these characters as being naturally inclined towards parenthood. They're wonderful people of course but Lois is a hard chasing, hard working juggernaut of a woman and Clark has rarely handled any family situation very well. I never imagined them as being incredible, flawless parents, and here they are living a relatively Rockwell-ian life. They got ten years to change and grow, but as a reader I didn't.
All that said, I'll take the Rockwell painting over crap like Lois leaving Clark because he didn't save her father (and refusing the go home even when Clark was dying in a hospital surrounded by villains) or Clark struggling with the temptation to sleep with Lori Lemaris.