You want a social worker to think prior to the first act of dismantling a family. We demand less of no one else involved in this process. A qualified immunity standard does not stop law enforcement from making arrests, using their weapons, or executing search warrants. It does help assure that they will not perform any of those actions maliciously. Most actual removals are made by law enforcement who already operate with a qualified immunity standard.
Doctors have no immunity.
But that does not chill a doctor from making the difficult life and death decisions he or she makes. It does assure that his hospital, medical group and insurer will have some stake in ensuring his professional competence and goodwill. Fathers who have lost their children forever to false allegations during custody disputes which were never adequately investigated or were actually promoted by social workers with an agenda. Mothers who have had their babies removed from their arms because of false allegations which have taken years to resolve. Children who have been the most profoundly affected victims of the insensitive, intrusive, intervention of government always with the bent of intentions.