Why it is important that many identical plasma cells are produced?
Many identical plasma cells can secrete a particular type of antibody in adequate amount to fight a disease causing microbe.
Each lymphocyte is able to produce antibody of only one type. Hence it must proliferate to produce several plasma cells so that enough amount of antibodies could be generated.
Plasma cells provide humoral immunity . Different batches of plasma cells are generated depending on type of microbes invading the body. Many plasma cells secreting same type of antibodies in adequate amount would ensure that the germs are readily killed and thus there will be no appearance of disease symptoms.