Brakes are a luxury, not a necessity, in general aviation. Enough forward planning removes the immediate need for the them.
This is not necessarily the case in abnormal operations, and not the case in normal operations, either. One should try to avoid brake use when it's not necessary. However, brakes may become necessary in a crosswind, to hold short of a taxiway or runway, during a runup, during a rejected takeoff (think of something entering the runway in front of you), steering in many light airplanes, and so forth. Brakes are often a necessity; hence their use in aircraft certification.