why is that better than a society where people have deep roots in their local community that span across multiple generations?
How's that working for the folks of Detroit?
I am from Detroit and moved to a better job and life in the Bay Area as soon as I was able (in 1985). Housing was expensive but the cost was worth it.
It's better in that people can move to where there's work so you ideally don't end up with a shortage of jobs in one place and a shortage of workers in another place.
International investors don't care where you put your roots.
People move to improve their life! If the want family ties, they can stay put, but historically they want a better, higher paying jobs and escape from racial or religious prejudices of their old surroundings.