This is from Up in the Sky, which I just read (and liked… a lot. Why can’t King write more stories like this one? But that’s a whole other thread ).My whole life, I wished to be what Ma and Pa taught me to be. To have lines. You don’t cross the lines. If you do… what are you?
If you read this quote I really don’t think it matters if Ma and Pa are alive or dead (Pa is alive in the story), it makes the same point either way. Frankly, I think this quote perfectly encapsulates how they should be used when they have passed on. The focus is what effect they had on Clark, what he does with it, and how it shapes who he is. I kind of prefer that they have passed; Clark honors their legacy by doing what he does as Superman.
But if they are alive, I think the best way to utilize them (as already mentioned a few times) is to subvert the overused superhero trope of parents dying thereby causing childhood trauma by simply having a “normal” parent child relationship. i.e. the opposite of Batman.
Just so long as they are well written (a cliche in and of itself, ha ), I don’t necessarily see that it needs to be mandated either way, alive or dead. Each has its merits.