Personally, I think Rockets should have a basic interior. Nothing in excess, but enough that it doesn't seems an empty iron rectangle that all you do in it is to stand inside, while you can barely see through the window.
After you get a Spaceship(assuming that Mic follows the logic of Rockets having up to Three tiers, and further than that requiring a spaceship), the interior would be way more fleshed out, possessing things such as aesthesical radars and similar details, AND useful information such as health(if spaceship battles are implemented), fuel and the such.
Hey, you may only use these rockets/spaceships to leave your planet, but that isn't to mean that they don't require any aesthesical features!