Those surface ghouls don't do anything right now, but yes. They will play more major role in future releases.
One of the bigger things I want to focus on in the future is to make the world more "real" and not just static setpiece.
There are some things that already change with time, like the bridge betting broken or the Villagers building the training grounds after one year passes, but I deffinitely want to add much, much more. And ghouls appearing on the surface over time is just one of those things.