It's even worse if you don't limit the velocity to sth like 30km/h - because then you need more space for turning and acceleration/breaking; and also noise incr

It's even worse if you don't limit the velocity to sth like 30km/h - because then you need more space for turning and acceleration/breaking; and also noise increases with speed - which tends to make people put their houses further away from the streets - which makes everything even less dense, which requires people to speed up and use cars more. So in practice it's worse than 10x.