You know, I was thinking about whether this game would benefit with the ability to drive cars at whim but I truly believe its better off. Lets face it, in EVERY open world game you can drive cars, right. Mercenaries, Crackdown, GTA, TRUE CRIME, but these games all revolve around driving because of it.
I think it really benefits the missions that there are no cars involved, the dev team has to make smarter placements of missions, use the verticality, and the actual missions themselves are not "follow this guy" or "go to this place at the end of the world". Its refreshing.