These theories are of a general and fundamental nature. Theoretical Biology is the logical counterpart of Experimental Biology, a situation that is well known from physics.
Many people oppose fundamental research with applied research.
Within this distinction, Theoretical Biology is mostly associated with fundamental research. This opposition is not correct, however. One can even question the value of applied research that is not fundamental. Biological science is highly relevant for all kinds on societal problems, like environmental pollution, health care, agriculture, fisheries and industrial innovation. These problems all require a quantitative treatment.