People may believe that chickenpox is usually not serious -- why not let people get the disease? While chickenpox is not serious in most cases, complications can occur, leading to serious health problems and, in rare cases, death. It is never possible to predict who will have a mild case of chickenpox and who will have a serious or even deadly case of the disease. Now that there is a safe and effective vaccine available, it is not worth taking this chance.
Also, even with uncomplicated chickenpox cases, lost time from school and work (as well as the cost of medications or treatment) can result in a significant cost for the family.