You could, but the main places where humanity is aren't so sparse. Even with the vastness of space, I feel Bethesda could have taken a little more steps to make the the immediate population centers feel like humans dug in and started to thrive.
I think of it this way, I spend half the time wiping out entire refimente of Spacers, Crimson Fleet, and Ecliptic. Those people didn't come from nowhere. Plus because of the sheer numbers, it feels like they outnumber just regular folk, and that lopsided feeling could be fixed with a different presentation.
The game does what it does fairly well and I don't think it needs DLC or mods to fill out the rest of the planets with content, so I've no expectation or desire for empty planets to change despite what I've been saying. Simply having more people around isn't going to change the typical experience, it would just be more lifeless dolls like walking through Night City.