Hi,
Those resistors are not required. They are mainly used as security to avoid spurious activation of the transistor.
Another point I have not detailed is the the difference between Hfe min and Hfe max of the transistors.
Whithout RX, the transitor is current activated (you inject ib). Whith Hfe min/Hfe max = 6 like with BC337, the voltage difference into R could vary from 1 to 6.
Whith the resistance RX, the transistor is voltage controlled. The current flowing trough R is, let say 10 to 20 times the ib current, so the voltage trough R is less ib dependant. You need only to have 0.7V between RX ends to activate the transistor.
In your case, you can try without RX as the delta between Hfe min and Hfe max is lower than for BC 337.
But if I would have to build the schematic, I would use RX and maybe use a darlington transistor to reduce ib and with this maner reduce the current flowing through R and RX (10 to 20 times ib).
In this case why not use an ULN2003 or ULN2803 which include several darlingtons with all the needed resistors.