The problem is that many kinds of objects go through a period in their potential lifespans when they don't "pencil out"—they're not worth keeping or preserving because they're not worth any money.
My favorite example of the Trough of No Value comes from a former acquaintance whose back room had a high, narrow shelf running all the way around it, about a foot below the ceiling. Arrayed on the shelf were dozens of kids' lunchboxes from the 1950s and '60s. He told me that not only are such lunchboxes collectible now, but that they're actually fairly hard to find. Time was, of course, when most every schoolkid had a little metal lunchbox (poor kids "brown-bagged it"). But the kids grew up, the school lunch program got started, and who wanted to keep old lunchboxes around? They weren't useful any more. They weren't worth anything. And, since they were almost all used for their intended purpose, many were damaged or worn by use (I vaguely remember owning one that was rusty and had a dent). People naturally threw them away. The "trough of no value" for lunchboxes was long and harsh. That's why they're not so common today as you might guess—because not that many made it through the trough.
That's why "being famous" is a great way to preserve your work—because value is the #1 preservative for old objects. But want to know another? Craftsmanship. One of the great hazards of survival through time is the lack of a market and a lack of trade value, but another is simply shoddiness. (I have to chuckle whenever I read yet another description of American frontier log cabins as having been well crafted or sturdily or beautifully built. The much more likely truth is that 99% of frontier log cabins were horribly built—it's just that all of those fell down. The few that have survived intact were the ones that were well made. That doesn't mean all of them were.) It's not just that things that are poorly made deteriorate more readily, it's also that they signal their own worthlessness. Or, in the case of an archive of photos, they might actually hide their own worth. I have in mind making a book of my best 35mm black-and-white pictures, for instance, and I have it in my head which pictures would be included. But if I get hit by a bus tomorrow, nobody will ever be able to extract that book out of the great motley of my hither-and-yon mess of negatives.
Please keep comments on topic and to the point. Inappropriate comments may be deleted.
Note that markup is stripped from comments; URLs will be automatically converted into links.