Lip skin is extremely thin, lacks most sweat glands and hair follicles, and has capillaries near the surface. If your entire body were covered with lip skin, you’d lose much of your normal protective barrier. You’d be extremely vulnerable to dehydration, temperature changes, and infections, and your skin would likely dry and crack constantly without constant moisturizing. You’d also appear reddish or pinkish all over, and physical contact could be painfully sensitive. Overall, such a condition would be debilitating and practically unlivable.
If ChatGPT was applying for the job: