I don't really see it as formulaic at all. People lose their parents all the time; it's a part of normal human experience, so it only makes sense that eventually Clark would have to go through it as well.
But lots of people
don't lose their parents, at least not while they're in the prime of life. In this day and age, there are plenty of people in their 30s and 40s and even 50s who still have both parents alive and well. So yes, obviously, losing parents does happen, but my point is that it doesn't
always happen, that there shouldn't be an absolute requirement that
every fictional character ever has to have at least one dead parent.
Not to mention that in most tellings, the Kents were already up there in age when they discovered Clark, so the likelihood is even greater that it would happen before he left home.
In most tellings
prior to 1986. Because, as I've already explained, when Superman was created, life expectancies were lower. By the time the late '80s rolled around and Superman's backstory was being rebooted, there were a lot more adults who still had both parents alive, and so that's how Superman's story was told in the comics for well over 20 years, in the 1988 animated series, in
Lois and Clark, and in
Superman: The Animated Series. And while
Smallville did eventually kill Jonathan, it most assuredly did
not depict him and Martha as being "already up there in age," but instead portrayed them as quite robust. John Schneider and Annette O'Toole were respectively 41 and 49 when the series began.
So no, it's not "in most tellings." It's only in most
older tellings. And that's my whole problem with the way productions like
Superman Returns and
Smallville take all their cues from Richard Donner's movie -- because they're ignoring the decades of progress the franchise has made since then.
Plus we're talking about the first superhero here. I think there have to be allowances for certain things seeming "formulaic", since a lot of them were originated with this character.
You're talking as though we haven't actually had over two decades of successful storytelling -- countless comics, two animated series, and one live-action series -- in which both Jonathan and Martha were alive during Clark's adult years. It has worked. It can work. It isn't even the exception to the rule any longer -- it
has been the rule for most of the past quarter-century, and it's only in the past few years that the old-school approach of killing off Jonathan has begun to make a comeback. Clearly, indisputably, it is
optional. It is not obligatory.