Unlike you, Ann, I started watching LnC at the age of 13, long before I started reading fanfic. Judging from season 1 and 2, I never really understood why Clark fell for Lois anyway. She was behaving badly and most of the time, I identified with Clark more than I could with Lois.
About ten years later, I discovered the boards and became hooked to all those wonderful fics out there. Most of them were trying to explain why Lois was behaving so badly, they were portraying her fear so much better than the show ever could.
The way the show is written, I guess, we're supposed to believe that Clark's love for Lois runs deeper than her love for Clark. Throughout the show Clark constantly says how much he loves Lois, it's mentioned in almost every episode. We see it in his eyes, his love is clearly visible.
Lois on the other hand hides her feelings, she ignores them, tries to push them aside. In my opinion, ToGOM is the first episode in which Lois really shows how much she loves Clark.
Until then, we've seen a whole season of Clark suffering from unfulfilled love. I think that clearly influences how we perceive their relationship.
Speaking of deathfics - I don't like them. I've always stopped reading a fic, however well it may have been written, when a main character was killed of. I like well written angsty stories, but this is a theme I will neither read nor ever write.
But thinking of the dramatic impact, I understand why a griefing Clark is portrayed more often than a griefing Lois.
1. A griefing Lois was part of the actual show. We already saw how much Lois suffered from Clarks supposed death. Knowing how devastated Clark was when he lost Lois to Lex, a griefing Clark is an interesting perspective.
2. Dramatically, a widower is more interesting than a widow. Judging from the common roles in marriage, she cared for the kids, she cooked, maybe she even went to work and earned money. So when the wife is left alone, she deals with her grief, but otherwise she already knows how to organize her life. Lois would certainly be one of those women.
When he is left alone, he doesn't really know how to keep the household, he probably needs to build up a real relationship with his kids because he always went to work.
3. Clark would suffer because he - Superman - couldn't save Lois.
4. And judging from the writer's point of view: It's easier to kill Lois, plain and simple - you don't need a decent A-plot to explain her death. She could die of a disease - having a villain is not essential.
And being a writer I know that a villain, particularly a new one, is hard work. You need to portray him, explain his motivation. Where did the kryptonite come from...
