Cladistics is now the most commonly used method to classify organisms. Well, it's obvious that a system of classification is needed. That is, we need words like beetle or conifer so that we can talk about many organisms at one time. In fact, the history of formal classification schemes in biology is long, dating from the 1700s, well before Darwin proposed his theory of natural selection. Today, cladistics is the method of choice for classifying life because it recognizes and employs evolutionary theory.
Cladistics predicts the properties of organisms.
As with any other system in science, a model is most useful when it not only describes what has been observed, but when it predicts that which has not yet been observed. Cladistics produces hypotheses about the relationships of organisms in a way that, unlike other systems, predicts properties of the organisms. This can be especially important in cases when particular genes or biological compounds are being sought. Such genes and compounds are being sought all the time by companies interested in improving crop yield or disease resistance, and in the search for medicines. Only an hypothesis based on evolutionary theory, such as cladistic hypotheses, can be used for these endeavours.