When to use them: when you've eaten a neck tail, boar meat, and raspberries while moving your furniture around, but now Smell From the Swamp is triggering. Or you want to explore a higher tier biome than your current location and need to eat better food. Maybe you need to change from three stamina foods because you were chopping wood and want to explore now. Instead of waiting till you can eat again, you can puke and then eat what you need.

Does it happen often? No, I've probably used them twice. But having a handful taking up one space in a chest costs nearly nothing, and gives you the flexibility to change your food if you need to. Bukeperries don't remove an aspect of strategy, they add another layer of strategy to food management.