One: Most plastics will creak eventually when flexed or moved without be structurally unsound. My old flip phone does so and it still works.

Two: You WANT a little bit of give on mobile devices because there’s a chance of it being dropped or knocked off a desk and impacting the floor. It’s the same reason why cell phone battery covers fly off, ejecting the battery if you drop it / kick it hard enough. It dissipates some of the energy of the fall, reducing the kinetic energy without going through the laptop itself.