Limited editions are strange. You can't predict what will be the best sellers, and if you guess wrong and then destroy negatives, then what? Wield gun, pull hammer back, shoot your own foot. I can understand why someone would get bored printing the same picture over and over again. On the other hand, just because someone makes only 50 prints doesn't guarantee anything. Maybe 5,000 prints at a lower price would pay off better (just to pick a big number). Rarity alone does not make it great. Collectors aside, I bet a lot of people do it so they can print the entire run in one big work session for consistency and then move on to other projects more easily.