Oh. That's no big deal. I can't walk the entire planet in real life either.
I wouldn't say it's "no big deal." It's just not what the game is, so you have to adjust your expectations and enjoy what is there.... but I don't like the change. Not when No Man's Sky demonstrated how to do far more openness in space years ago. Bethesda has far more resources, they couldn't even get close?
What happens is that on a planet there are a handful of permanent things, like cities.
Anything else, you select a place to "land," your ship, and the game procedurally generates a mini sandbox based on the planet's stats and where you picked to land (ie, if you pick to land on a coast, it will generate a coastal map, if you pick in the mountains, it generates a mountainous map, etc). It then populates the mini sandbox with procedurally generated things like pirate outposts or dungeons.
But the problem is, this is all random and temporal. You only get 4 landing spots on a planet. After that, if you land at a 5th spot on a planet, it erases the first spot. The dungeon you explored is literally wiped from existence in the game.
From what I've seen so far, the way they are combating this temporal nature is that the mini sandboxes that the game is generating for you to walk around in... are so boring that you don't want to walk all the way across one. There is nothing IN them, except the procedural outposts or dungeons or the random space mudcrab you come across to shoot.
Skyrim's whole world felt like an adventure. "What is over that next hill?" and "I want to get to the top of this ridge to see what I can see." Whereas the dungeons in Skyrim, though more hand-crafted than say, Oblivion, tended to get real stale real fast.
Starfield feels like the opposite. There is no real world to explore, but their procedurally generated "dungeons," which are randomly created and populated in your landing zones, are the meat of the game. In this sense, it's good that the gun play is better, because the dungeon clearing is going to be the game's highlight, not the exploration.
But it also leaves the writing (main quests and side quests) as the hook that you have to follow. Doing side quests and side content to lead you to the dungeons to clear. If you are expecting to get lost exploring the map, nope, don't bet on it. How could you? There isn't even a static map to get lost exploring. There are no points of interest worth exploring because literally anywhere you put your ship down can be erased.
I really, really don't like the fact that when you "warp," to a planet, you are placed in orbit above the planet (this is the game's staging area for space dogfights), but it's all just scenery. You can't actually fly down to the planet or to another planet.
I even understand that they can't make an entire open world galaxy, that they can't let you fly from one star-system to another. It would be just too massive. But they can't make the individual solar systems explorable? I can't fly from Earth to Mars?
That should have been possible.
I don't think their ancient game engine can handle it. But then it should be scrapped and they should build a new one from the ground up, because other companies are lapping them in that regard.