Hmph, who told you that? If the motor has stiff wires like bk/feigao etc. cheap style motors. Then it's nono.
But in castles neu motors have the noodle wires. IIRC the castle recommend to cut the wires for your needs. Even I did in my g2r. You can look my thread its somewhere here..
Anybody correct me if im wrong..
If the wires length won't bother you, then dont cut 'em. Long wires are good for future purposis, if you wan't to use your system in some other car where you would like to have longer wires. Example you don't have room to mount the esc and motor close each others..
Shorter wires goods are then neater look, interial resistance decrease and the wires won't wobble in the car while running which can cause the plugs disconnection...
If im wrong then someone shut me up