Why is a receiving circuit in e.g. RFID made resonant with a parallel capacitance instead of a series capacitance?
That's because the model you are assuming does not well replicate an rfid receiver.

The EM wave that couples with the coil produces some varying voltage at the coil's terminals, so the voltage generator, with a series resistor if you want, should be in parallel with the coil. Now the best you can do is adding a parallel capacitor so that the LC parallel resonates at the right frequency provoking a very high voltage gain (not power gain).