Hi,

What i think is that these inductors and capacitive networks are used to remove the imaginary part of the impedance of the dipole or monopole antennas and match it to the real output impedance of the I.C. pins. It also can be catering for the imaginary part of the impedance at the output of the I.C. pins which are also not purely resistive loads.

The discrete  off-chip components today are very accurate but always prone to size issues .As the frequency of the circuit operation increases the connecting strip-lines or microstrip lines are becoming smaller and smaller and hence the off-chip components are way too large in size and prone to parasitic effects. Hence we can use microstrip based inductive and capacitive networks for impedance matching which can take much more area than a discrete component.But in majority applications  values of capacitance and inductance are only realistically achievable by using off chip discrete components.

Regards