The racing radios we are using arent just made on/off road racers. People with crawlers, bashers, scaled offroad vehicles etc will use these radios as well and the extra channel/buttons allows the user to do a lot more with their rig like rear wheel steering, winching, high/low range gear box, reverse gear, diff locking, turning on and off lights, gyros, channel mixing etc etc.

You should also be using the extra buttons on your radio as well. most importantly the trimming and dual rates for both steering and throttle to find tune your car and driving. Assigning one button to activate a countdown timer to let you know your practice run time is up to prevent over draining your batteries is also a good idea.