Some of the items in a microwave meal are designed to lose moisture at a, more or less, specific rate. By peeling the corner you alter the rate from that which the manufacturer prefers to ensure the highest possible quality. You may find that you enjoy the items more or less by changing the "cooking" process. I prefer drier vegetables for instance. Your mileage may vary.
Oh, thou clear spirit, of thy fire thou madest me, and like a true child of fire, I breathe it back to thee.