Not sure, but I guess in the long run when you have shops and stuff you can use the settlers and assign them to the shops, which can be a way of making money or resources I think.
This basically.
The larger the community, the more money you make from shops. I am getting a steady amount of caps just from 12 people in Sanctuary, get caps from Workstation every time I visit.
Also, makes setting up a supply line easier with spare man resources.
When you get the Greygarden settlement, you can assign the robots to do the farming, freeing up man resources for defence, provision etc
Also, how long does it take for dead bodies to disappear, if at all? I removed everything on it and I still have a pile of naked dead bodies in...
Covenant, after everyone turned on me