hi,
smd is a general trend now days because of many advantages , one of them is that production costs can be reduced since there is no need to drill holes trough pcb (1 operation in minus in technological flux), and of course devices get smaller . The circuit requirement is also important, in radio frequency ranges smaller devices, shorter connections/tracks are preferred. Still, trough hole devices can't disappear because they offer also qualities that smd don't have. They usually offer better thermal dissipation of the heat generated by the device and a better mechanical integration in the circuit (in the case of larger components)