The job description writing process can be seen as boring by many line managers. However, the job description is always a basis for the modern Human Resources Management. Most value added HR Processes depend strongly on job profiles, job descriptions or job roles. They are needed as HR Professionals can see a big picture of the company.
The modern job description is a document that puts the new job into the context of the organisation. All employees can see key responsibilities, inputs and outputs. They can easily compare differences between the proposed role and the reality.
The HR Manager has to be a master in a class when the line managers needs to write a new job description. The line manager should be the person responsible but HR has to set up a team that will challenge the new role as the organization benefits from it.