The problem is that you don't know if the virus is going to mutate to become more lethal/virulent or less as time goes on. Each identified outbreak that passes a certain threshold needs to be treated as a potential pandemic. The risks of letting another Spanish Influenza or Ebola go global are not worth it.

There is also some unsubstantiated talk (CDC has come out and said it's not evidence supported yet) that this virus can spread before the host shows symptoms which is unusual. Your healthy coworker could come into the office and infect everyone, then come down three days later with the symptoms, and a week later the whole office is out sick. Or school.