This cheat is definately a necessity for exploration. In addition to this, a godmode cheat was inplemented in SA, which also helps cruising and exploration aswell. I remember when you drove through LS in a recently modified car, when a bunch of ballas gangsters showed up and started to open fire. However, this might not make any difference in V if NPCs wouldn't randomly attack you. It also doesn't help for exploration, since it protects your healthbar for everything, except for falls from big heights and explosions.