New Atlantis actually feels even smaller when that one guard next to the landing pad can finish delivering his only line every time you haul 1000 kg past him.
Bethesda has always had an approach to designing cities where they feel you must be able to enter every building and talk to every NPC. You can see this since at least Morrowind. This design constraint makes it prohibitively expensive to design large cities with hundreds or thousands of inhabitants. That's why you see "cities" in Bethesda games with several dozen houses at most. In Oblivion, there are less than 200 people living in the capital of an enormous empire, the imperial city (300 if you count the guards). Skyrim has a total population of 700 or something.
In the Witcher series they don't feel the need to do this and can just plop down buildings without any interior, and NPCs that only give you a generic voice line. That makes it feasible to create larger cities, although there's a sort of suspension of disbelief required. Most of the people you meet don't actually have a house and just walk around. If you try to investigate the city as more than decor the illusion quickly falls apart.
Not saying one approach is better or worse than the other, just different tradeoffs.
And the problem with Starfield's cities is that they didn't do that. Since Oblivion the charm of Bethesda's city design was that every NPC (who wasn't a guard) had a "life" of sorts. They'd tend to their businesses, but they'd also go home and sleep at night, go to the tavern in the evening, visit friends, etc. None of that is happening in Starfield, and as a result the cities just feel dead.
Also, Bethesda cities have hundreds of lootable objects, something most other game engines couldn't handle. As sushibowl says it's different tradeoffs.
I guess they could have designed the major settlements with decorative but unreachable districts surrounding the playable core to give the illusion of size but - oddly for a game with so many loading screens - they chose to have it possible to just walk out of the gate instead.
I actually felt like I had to suspend disbelief a lot more in Skyrim than Witcher. Witcher at least felt believable, but then I go to the “Cloud District” in Whiterun and it’s the size of some guy’s porch. It just made the world a bit hard to take seriously. I’m not saying that Skyrim is a bad game, I enjoyed the hell out of it, but I definitely preferred Novigrad to anything in Skyrim. Still plenty of places to go in Witcher.
Also from what I understand, Witcher had hundreds of people working in it, but Bethesda still sticks to a fairly small team size, which I’m not convinced can be competitive in a AAA space after seeing starfield