It's thought that they may have evolved such an excruciating defense because they forage in rainforest canopies loaded with predators looking for proteinaceous snacks.
The complex arrangement whereby proteinaceous enzymes (which orchestrate a cell's chemistry) are encoded by DNA (which does the information storage) could not have appeared from nothing.
They're a little bit less proteinaceous so I tend to have the powder more often than I have these, but these are also very handy if you really do want to save time.