Cost models also create a repeatable process enabling managers to apply this model to multiple situations - i.e. if attrition goes up by 2% what will that cost the business vs. if attrition goes down by 6% what will that save the business. Through this business process, the company can develop a metric that becomes the standard expected rate of return for projects.(i.e. what is the expected rate of return on hiring someone).
(This can be compared to customer analytics projects calculating the expected rate of return for customers. Many customer analytics projects today calculate the expected rate of return - or even predict the lifetime value of a customer. This exact approach is applied with calculating employee value)
Cost Models safeguard the company from losing money when engaging in activities (like hiring, exiting or promoting) that seem profitable but really are not.