loosening or removing the straps reduces the ski pressure, reduces steering effort but it also means the sled will not turn as well either. It also allows the sled to transfer weight more quickly during acceleration causing the skis to come off the ground. If you don't have the straps I am betting you had a hard time steering through tight turns and the sled wanted to go straight during acceleration. You definitely need the straps to help you tune the supsension to your desired level of steer-ability and steering effort as well as ride comfort.
Mills