I think it's safe to say we will be getting land vehicles and landing gears at some point down the line, and the only reason we don't have any yet is because there are bigger priorities (tutorials, improved new player experience, stations/cities, factories, etc.) and because right now there's just no use for them. Moons are completely barren and un-mineable, planets don't exist yet, and there isn't even gravity. Once we see gravity and content added to the moons, I'm sure land vehicles will follow after. Or at least dedicated landing gears.