'the evolutionary scapegoat'

Appendix isn't a very good example. It serves in an immune system role in your body, with many lymphoid follicles. It manufactures serveral kinds of antibodies, such as IgA, IgM and IgG immunoglobulins. Studies have shown that its presence reduces the occurence of ulcers and bowel cancers in humans (I recall a study in which in a sample of people who had cancer of the intestines, 84% of them had their appendix removed, and in a control sample, only 24% had their appendix removed).