Roadless forest keeps the natural habitat intact, I remember driving through Carson national forest in NM, and saw how a highway or even a forest road would cut the landscape, divide the habitat.
Roads require maintenance, weed control, and other invasive methods to keep it from getting reclaimed.
Roads also cause unnecessary flooding and runoff, and introduction of foreign material into the pristine waters and soils of national forests.
Most fires are started close to roads. So there is an increased risk of wildfire as well.
I am therefore against the roads in the forests.