Why do we need a distinct subspecialty of Theoretical Physics?

All sciences use theories and models. Some of these theories and models have limited very specialized application within the field, some have extremely broad implications -- e.g., Darwin's Theory of Evolution in Biology, Freud's psychosexual theories in psychology and psychiatry, Karl Marx's Dialectical Materialism in Economics, Quantum Mechanical electronic orbital analyses in Chemistry. However, Physics would appear to be the only science in which Theoretical analyses are given the distinction of being a unique subspecialty in which professionals make a career of specifically, and exclusively developing theory as an end in itself, and as a means of advancing knowledge of natural science in itself, with or without experimental justification or foundation. Why is this the case? Why is it necessary? Why should the objects of study for physicists require and/or benefit from theoretical analysis in the absence of experimental foundation more than in any other science?