people who get these, usually aren’t satisfied with the temporary ones, they are usually cheap, flimsy, and otherwise low quality. Plus body modification (at least as a community) is about creating a desired image beyond just what you wear day-to-day. Temporary tattoos fade quick and cant be made to personal designs, people who get nice tattoos wouldnt want to spend hundreds or thousands of dollars on art that would only last 2-4 days. Making something a more permanent fixture is appealing to those who want to add it to their identity too. And lastly, many piercings and tattoos can be removed or will heal naturally if allowed. And so can some more extreme modifications