Is the game meant to be lively when you have missions to complete?

[Xavierr]

Is the game meant to be lively when you have missions to complete?

 

I'm starting a new campaign and I'm noticing more cars are spawning, traffic is heavier, and more npcs walking down sidewalks.

 

When I had the main story completed the only car to catch my eye was the feltzer and they were everywhere, and the traffic was a lot less.